"For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him should not perish, but have everlasting life." —Jesus Christ, John 3:16, King James Version of The Bible
The world's biggest single religious group tends to be a bit misunderstood at times, even by its own adherents. Since only one in three people worldwide describe themselves as Christians, it follows that at least two out of three people are a little vague on what it is all about.
Christianity is a monotheistic religion that originated in what is now Israel in the 1st century A.D. as an offshoot of Judaism. It is based on the teachings of Jesus of Nazareth, a rabbi and preacher whose followers identified Him as the Messiah promised in the Old Testament, and who was executed by Roman and Judean authorities for supposedly presenting Himself as such. Originally one of several reformist sects of Judaism at the time, the movement of Jesus' followers opened its doors to non-Jews some time in the first hundred years after Jesus' death and gradually became a religion separate from if still linked to Judaism: Christianity. Christianity spread throughout the Roman Empire, despite systematic persecution of Christians, and in the 4th century became the official religion of the Empire, and thereafter the dominant religion throughout Europe and the western world.
Most Christians can agree on at least that much. Most, anyway. There are in-house disagreements on even these bare bones of its history. In fact, you can make a good case that a defining attribute of Christianity is the wide variety of ways the teachings are applied in religions.
A few basic points that the majority of Christians agree on; any disagreement will be mentioned in the entry for the appropriate sect!:
Christianity is a monotheistic religion from the perspective of modern adherents. The most prevalent view is that the one God subsists in three persons: Father, Son, and Holy Spirit/Holy Ghost. Needless to say, a lot of philosophy and theology has been devoted to understanding this, and it's still a Mind Screw for many. Some sects do away with it entirely, probably for that reason.
God is omniscient (i.e., knows everything that has ever transpired or will transpire, past, present, and future), omnipotent (i.e., capable of doing anything He desires to), and omnibenevolent (i.e., He loves everyone and everything). As above, a lot of philosophy has been dedicated to comprehending how these qualities interact with each other, and how they can coexist given the seemingly contradictory nature of the world man exists in. The general answer is that God is playing a long game, the understanding of which is beyond man's comprehension.
Christ is not Jesus' last name, but His title designating His role as Messiah and Savior. It comes from the Greek Christos, meaning "anointed", in turn a translation of Māîăḥ. This is why phrases like "Passion of the Christ" make sense. Note that this also means that referring to Jesus as "Christ" or "Jesus Christ", rather than just "Jesus", constitutes an implied claim that Jesus was, in fact, the Messiah, and thus should be avoided when you're trying to draw a distinction between the Christian view and the "historical" secular view of Jesus. Those who wish to refer to Jesus is a secular or historical way can refer to him as simply Jesus, as he's pretty well known, or Jesus of Nazareth if you want to be specific ("Jesús" is a fairly common male name in Latin America, and to be honest the word "Jesus" is the result of a game of interlingual telephone for "Yeshua"—a name that appears in the Old Testament, where it is translated "Joshua"note English translations of the Bible since the King James Version have relied on the Hebrew Masoretic Text for the Old Testament, while the New Testament is usually compiled from primarily Greek sources. It would not have been immediately obvious to early translators that the Greek Ἰησοῦς Iēsous and the Hebrew יְהוֹשֻׁעַ Yehoshua/ישוע Yeshua were the same thing, and so the distinction stuck. Spanish translators were aware, however, so there are plenty of men named "Jesús" in the Spanish Bible—and now you know why "Jesús" is a common name in Latin America: in Spanish, the Son of God happens to have been named Josh.).
Jesus was the incarnation of God on Earth. In the person of Jesus, God walked among us and experienced human life as a human, including its sufferings and its privations. Don't ask whether Heaven had an "Out of the Office, Will Return In [X] Years" sign on it whilst Jesus was alive. That view is called "modalism", and is generally considered a heresy formerly known as Sabellianism.
Christianity is an expansion on or replacement of the covenant established between God and the Jewish people in the Old Testament. Key to this is the concept of blood sacrifice — when sin transpires, blood must be spilled in its atonement. Whereas the ancient Jews fulfilled this necessity with intermittent animal sacrifices, Christ offered His own blood as a substitute, permanently, once and for all. Hence the sobriquet "Lamb of God"; whereas lambs were the preferred animal for sacrifice in the temple, Jesus became the lamb for the entire world.
Sin is an inexorable part of the human experience, owing to Adam's original act of defiance to God by eating the forbidden fruit (i.e., Original Sin). No matter how pious a life one may try to lead, it is inevitable that at some point one will commit a sin intolerable to God - and thus, divine salvation is necessary for all souls.
Most Christians, now and throughout history, obviously have had sex. Sexual morality, most universally in the form of refraining from sex outside of marriage, is of great importance for many Christians.
The Christian faith is by no means restricted to those who are "perfect." In fact, Jesus Himself often lectured hypocrites, especially those who saw themselves as "perfect", and hung out with sinners (a fact that really pissed off His opponents). Christianity is in fact a religion that embraces sinners; this doesn't mean you keep sinning, though. The emphasis is on on the process of sanctification — becoming more conformed to God's will each day — with God's help. It's not a "Get out of Hell Free" card, but rather the idea that, since God's love and grace are absolutely infinite, there isn't a sin you could imagine that He wouldn't forgive you for if your desire for forgiveness were sincere. Literally the very first step to becoming a saved Christian is admitting that you have sinned in the past, you are sinning right now, and no matter how hard you try, you will continue to sin in the future. Then, you admit that you need God's help and love to overcome your sin, then finally believing that such a God exists.
Traditional grammatical convention dictates that pronouns relating to God or to Christ be capitalized (e.g. "Him", "You", "His"). This also includes pronouns referencing Jesus and the Spirit, as they are also Him. This is done simply out of respect and is not a requirement, nor is it always practiced by non-Christians (never mind how thorny this would be for scripts that don't have capitalization, such as Hebrew, Japanese, Chinese, and Korean). Recent English-language Bibles rarely employ this practice. In addition, God's "gender" is an issue of huge debate; it's implied in the Bible that God doesn't have a gender, and Him is just a convenient handle, while others see the Bible as implying God as definitely male, or at least masculine. There is also little doubt that God-the-Son in the form of the flesh-and-blood Jesus who lived 2000 years ago was actually male. Some people even argue that God is the Father, and Jesus is the Son, and the Holy Spirit is, in a sense, the Mother; A "Perfect" Family, if you will.
A side issue: Jesus' historicity. The question of His holiness, position as Christ, and so on are obviously beyond the scope of scientific inquiry as they are not falsifiable. Jesus Himself left no writings that have survived to the present day, and the earliest Christian writings known today (the epistles of Paul) date to between fifteen and twenty years after His life. It is generally accepted as fact that Jesus, as in the individual described in the Bible, did, in fact, historically exist. This continues to be dicey, since the claim that Jesus the guy exists needs to be sorted for different notions of "exists". Was there an itinerant preacher guy named Yeshua somewhere in Judaea around AD 20-40 who made a stir and got offed by the powers that be? Almost certainly. Did that guy say or do anything ascribed to him in the Bible? Less certain. Was He born on December 25th of the year 1 B.C.? Almost certainly not, since modern archaeologists believe King Herod (during whose reign Jesus is said to have been born) to have died several years prior, and the date of Christmas to have been set by the early medieval church to coincide with competing winter solstice festivals.
The simplest definition of "Christian" is a person who calls themself a Christian. Unhelpfully enough, this doesn't actually cover all Christians (such as Messianic Jews), and it most certainly doesn't do anything to inform us of who is actually practicing the religion and who simply says they are. A slightly more complicated definition would be one who believes in the divinity of Jesus Christ and strives to live their life in accordance with His teachings. Of course, depending on who you ask, this means different things.
Protestant Christians believe a Christian is one who acknowledges s/he is a sinner, accepts Christ's offer of salvation, is forgiven by God on Christ's behalf, repents and changes his or her life to reflect this, and spreads the word to others. However, there's a bit of variation between denominations regarding whether humans have to initiate this process to be saved, or if God just does it anyway regardless of explicit acceptance. Protestants also claim that the Bible is the ultimate and only necessary authority for knowing how to live a Christian life, but also say that it is largely up to the individual to interpret the Bible's instructions as to how to live their own life (though the learned advice of the clergy is not to be discounted).
Catholic Christians believe that the Pope is the rightful successor of St. Peter, who was given the authority by Jesus to guide and direct the Christian Church on Earth, and that faith alone isn't sufficient except combined with acts. Basically, same as above but the Church (e.g. Pope) is the final earthly authority for figuring out how to actually do it and that it isn't enough just to believe in Christ, you also have to act like you believe. Contrary to common misunderstanding, they do believe in the Bible as strongly as Protestant Christians do, but their belief in the Church's authority simply means they do not believe that God's word consists of the Bible alone — it didn't end with the last period of Revelation, but rather, has continued throughout history. The term "Roman Catholic" is both misnomer and was once a derisive term. Their official name is simply, "The Catholic Church," which has many liturgical variants, or rites, but all believing in the same core values mentioned. The Roman, or Latin Rite, is what resides in Rome and is the liturgy seem most by Westerners, including the U.S.
Eastern Orthodox Christians agree with Catholics on the role of the Church as the earthly authority that can make statements of doctrine. But instead of the Pope, they rely on ecumenical councils (basically, gatherings of all the bishops in the world, where each of them gets one vote) as the final authority. The last ecumenical council recognized by the Orthodox was held in the 9th century, though the Catholic Church has held councils of its own since then, and the Orthodox have held synods (similar meetings of bishops on a smaller scale) numerous times since; plans have been in the works for a new Orthodox council since before World War I, with the latest plans being for a big council which it is hoped will be considered ecumenical in 2016.
Some liberal denominations reject the notion of external salvation entirely, and only focus on Jesus' message of compassion and forgiveness while not focusing so much, if at all, on His teachings on personal morality and sanctification. Others keep the focus on the personal morality and sanctification, but express it through acts of charity and giving — many major charity organizations around the world are run by Christians, and many hospitals and ambulances worldwide originated as Christian organizations.
As you probably already know, Christians are not one collective bunch. Much like in most religions, disagreements over theology and dogma have resulted in everything from quiet splits to devastating wars, in the past and even today. In Christianity, this has resulted in the notable tendency to create new churches, and this in turn leads to the large number of different Christian churches.
Amongst these disagreements (and a comprehensive list would be literally impossible) are:
This section is not a test. These are rhetorical questions. Answering them is not something a wise person would do.
The Nature of Jesus: How does Jesus being both Man and God work out? Is there a dual-nature (the "Chalcedonian" position, called "hypostatic union") a unified single nature (when claiming the unified nature is somehow fully human and fully divine, this is called "Monophysitism"), or what?
How can the doctrine of the Trinity be maintained without collapsing the persons into one or splitting them into three separate Gods?
Just what is the Holy Spirit, to be precise?
Circumcision. Paul says it's unnecessary, else God would have done it for us. Can we do it (for non-medical reasons) anyway? Are we still required to? Do we have to? Is it encouraged but not required? Discouraged?
Should we be baptized as in Matthew 28:19 - in the Trinity, or in Acts 2:38. in Jesus' name?
Is gambling cool? Does insurance count as gambling?
If Jesus turned water into wine, is drinking at all a sin? Was it really wine or just grape juice?
May women be ordained? For that matter, do we really need ordination at all?
Baptism — as a child, as an adult, at all, full immersion, sprinkling on forehead will do, one time only, or can we all just agree that we're glad we don't have to be circumcised?
What happens if I, despite being a model Christian, forget to get baptized?
Communion: Did Jesus say that the bread literally was his body and the wine literally was his blood? Was it purely symbolic? Neither? Cannibalism? How does this square with vegetarianism?
Is fighting and killing other "Christians" in a Just War okay with God? For that matter, what exactly is a Just War?
Homosexuality: Can we all just agree that, regardless, we share the world with everyone and leave it at that? Or is the issue an important one that doesn't allow for compromise? Does the prohibition only apply to situations of rape or dubious consent, or does it apply to consenting adults as well? Are same-sex marriages valid?
Sex: Is it better to be celibate, married, or just fool around? Is it OK to have sex with someone you love and are in a long-term relationship with (and maybe eventually will marry), but are not legally married to, or do you have to have a wedding ceremony first?
When can someone get a divorce? Is divorce even real, or is it just a legal term instead of a spiritual reality? Can someone remarry after a divorce, or must they remain celibate?
What exactly is God's name? Jehovah? Yahweh? YHVH? Jesus? Yeshua/Yehoshua? Eloh? Al-Illah? Allah? Adonai? Abraxas? Lord? The Lord? God? Bob? All of the above? Or are we not supposed to ask?
Is evolution a lie construed by Evil Atheist Scientists, or a legitimate way to interpret Genesis? Is the story of creation a literal account of how the Earth came to be, or a metaphor for events and lengths of time Bronze-Age man wasn't ready to comprehend?
Is intelligent design a viable fact, a diabolical attempt to pander to the pagans, a wishy-washy suck-up to the powerful proponents of evolution, or an unnecessary and pseudo-scientific attempt to "reconcile" evolution with faith when there is not really a conflict?
Theistic Evolution: Is evolution just part of God's plan where the causal chain from the big bang to the human soul is according to His will?
Purgatory: Do some/many/most/all souls need to finish being purified after death in order to enter Heaven? How long does that take? What might it entail? Can/should people on Earth pray for deceased relatives and friends to get them out of Purgatory faster?
What happens to the righteous unbelievers? Are the worthy heathens able to convert in the afterlife? Might they be given a chance to convert at the moment of death if they were sincerely doing the best with what they believed in? Does it even matter what they believe, or will their acts of good get them saved despite never accepting Jesus? Or does God suss out who's willing to accept Jesus and take extraordinary measures to ensure that the Gospel gets to them — not needing to go so far with the many who wouldn't accept even if they knew?
What about people who died as unbelievers because they never heard about Jesus, or were too young or mentally infirm to understand? What about the millions of people who lived before Jesus? Is there a "Limbo" between Heaven and Hell where these folks' souls go, do they get a free pass to Heaven, or are they condemned to Hell? And is this Limbo a place of joy, punishment, or both, or neither? Similarly, does a baptism performed on someone who doesn't understand it, or is too young to understand it, "count" as far as salvation goes? And what happens if this person later gains the ability to fully understand what baptism and salvation are all about? Do kids eventually reach an "age of reason", beyond which they're accountable to God for their beliefs and behavior, but before which God considers them too young to know any better? If so, what is that age?
Is religion actually an example of God's love refracted through culture and history, or is belief more like a valid passport?
Prophecy: How can I tell who's talking to Him and who's talking to himself?
Did Henry VIII suck at running a church and screw up Anglican apostolic succession?
And that entire Reformation business, justified? And whose fault is it?
Resurrection: Who? When? How? And what happens in the meantime?
What is the Apocalypse of John about?! Is it a prophecy? Political allegory?
Should every word in the Bible be taken literally, or should it be analyzed like a literary work for different symbols? Both? Neither?
How does one go about interpreting the Bible literally? How literal is literal enough? Jesus taught in parables; does that mean the Bible as a whole should be taken as a spiritual parable? Or can we just pick and choose the bits to take literally and consign the rest to poetic allegory?
What is the Bible? What books should compose it? Why is the Book of Jubilees in Ethiopian Orthodox canon but not Protestant canon?
What about breaking up Biblical texts into chapter and verse?
Was the Bible written and compiled by man, by God, or by both? If the text is "inspired," what does that mean?
Should we care about saints? Are some of them just poorly concealed rip-offs of local pagan deities? Or are they genuinely holy people who continue to care about people on Earth even after their own deaths? And how much power of intercession do they have anyways?
Miracles — does God personally intervene in people's lives to their benefit, or is He more of a cosmic watchmaker who observes but does not interfere?
If there are so many issues Christians disagree on, does this prove that God is a fan of the art of debate? Or is there one true church that is right about all the major issues, and everyone should join that one? And how in the world do you figure out who that one church is?
Is the King James Version of the Bible a great Bible, or the greatest Bible? Or is it written in extremely outdated language and based on somewhat sketchy source material influenced by political concerns? Should my Bible be precise? readable? poetic? And don't even get started on whether words should be translated as "young women" vs "virgin."
Speaking of archaic language, what's the deal with obsolete informal pronouns? Do they actually give a better sense of intimacy with God or do they just end up sounding even more formal because they're so rarely used?
Does God have a gender?
Was Jesus' manifestation in 1st-century Judea a one-time event? Is it possible that similar figures in other world religions were also manifestations of Him? If they are, does this mean these other religions are true? If intelligent life exists on other worlds, are they subject to the same covenant that human beings are?
Is Judgment Day coming soon? Is the Book of Revelation a literal account of things to come, or an allegory for events occurring at the time it was written? Will the righteous ascend bodily into heaven before the Tribulation begins? Will there be a Tribulation at all, or will the end times sneak in like a thief in the night?
Do Jews need to accept Christ to be saved, or does the Old Covenant still apply for them?
Liturgical language: What language should be used for public worship? The local vernacular? Or Latin? Greek? Coptic? Angelic tongues?
Polygyny existed in Old Testament, the New Testament and onward (thus, today); it is allowed? Forbidden? Discouraged? God just happened to made exceptions in the past? God actually dislikes it but allows it? God liked it? It was the invention of machist writers? If we permit polygyny, do we or should we permit polyandry?
If a couple gets married in a civil ceremony, is that valid in the eyes of God, or does the marriage only count if they are married in a church? What about cohabitation?
Does "outward holiness" matter, or is it what's on the inside that counts? If it does matter, then how does one define a "godly" appearance?
Is it OK to wear makeup and jewelry, or to have cosmetic surgery?
IS it OK for women to wear pants or cut their hair short, or for men to grow their hair long or wear a skirt? Or are men and women supposed to look and dress a certain way?
Contraception: is that OK? A gateway to abortion, or a completely separate thing? Are married couples supposed to produce as many children as they possibly can? Can they limit the number of children they have, or choose not to have any children at all? What method(s), if any, are permissible? Was/is "be fruitful and multiply" an order, or was it more of a blessing or a suggestion? How does that mesh with being stewards of a planet with finite resources? Is using birth control "messing with God's will," or is God's will flexible?
May infertile couples who wish to have children use drugs or IVF to conceive, or just pray, have sex, and hope for the best? What about the "extra" embryos produced in IVF? Is infertility a divine punishment on one or both halves of the couple? A test of faith? Just random? Might they be called to do something other than start a family?
At what point does life begin? Is killing an embryo the same as killing a newborn? Are there any circumstances under which an abortion might be permissible, or do Good Girls Avoid Abortion always?
How much influence does God have in the day-to-day lives of humans? Why does God allow bad things to happen?
Is there actually a Satan, or is that just an excuse for our bad behavior? If there is such an entity, how much influence do they have? Does denying the existence of Satan deny the existence of God and/or vice versa?
Can Christians fall from grace or be in danger of Hell, or is it that once they're saved (however that happens), they're guaranteed to go to Heaven?
Are men and women equal, or has God ordained one to be superior to the other? Is one spiritually weaker inherently, or is that on an individual basis? How much power and influence can a wife have over her husband? Must she always submit to him? Does she even have to? How much power and influence can a husband have over his wife? Are men and women meant to be in separate spheres? Can a woman own a business or work outside the home? If so, does she need permission from her husband (or her nearest male relative) to do so? Does she have to give up her career once she's married or has children? Is she restricted to "feminine" careers, like teaching or nursing, or can she hold any career she wants? Is a man who chooses to stay at home with the kids violating the natural order of things, or does he have the right to do that?
Is dating permitted? If so, does it always have to be with the end goal of marriage? Does a suitor require the approval of the woman's father? Is a chaperone required to supervise the couple's "interactions?" Is it OK for a Christian to date or marry a non-Christian? Is it more trouble than it's worth? Are Arranged Marriages the way to go?
Do bad things only happen to bad people, or can good people experience tragedies, too? Can prayer, good deeds, and living a certain lifestyle influence what does or does not happen to you? Why does a supposedly loving and compassionate God allow tragedies to happen? Why does He/She/It choose to intervene in some people's lives and not others'?
How much responsibility do we have to take care of the Earth? Are we meant to conquer it, or to care for it? Do we get a new Earth in the afterlife, or is this it?
Can living a "godly" lifestyle make you (materially) wealthy? Is it OK to be rich, or to become rich? How much of your income, if any, must you give up? Do money and material goods necessarily corrupt people? Should church buildings be austere, or is it OK for them to have valuable items? How much can a pastor make? Should they generate income at all?
Is tithing necessary? Do you have to donate 10% of your income to your church, or is that just an arbitrary number? What about people who can't pay this "church tax?" Are they still welcome?
Who makes the decisions pertaining to a denomination or a congregation? A pope? A bishop or parson? A council made up of ordained leaders? Lay people? Both? Neither?
Are we rewarded for believing the "right" things and/or doing good deeds here and now on Earth? Or is our reward solely an afterlife thing? What forms might these rewards take?
Who can become a monk or a nun? What kind of training do they get? Is this a lifelong thing, or can they leave? Are they strictly contemplative, or do they do other stuff, too? Can a parent dedicate their son or daughter to be a monk or a nun, or must that be up to the individual? Can monks and nuns be married, or are they to be celibate? Can they own property? If not, to whom do any possessions they might have or make use of belong?
Is a marriage dissolved when one spouse dies, or is it eternal? What if a widow(er) gets remarried; to which of their earthly spouses (if any) are they married in the afterlife?
Do we have to follow the Jewish dietary laws, or no? If consumption of blood is forbidden, does that extend to transfusions? What purpose do/did those laws serve, anyway?
How concerned do we have to be about "causing others to stumble?" Does this extend only to people we know personally, or do we have to worry about causing strangers to stumble?
Are the "brothers and sisters" of Jesus referred to in The Bible literal or figurative? Might they be Joseph's children from a previous marriage? Did Mary have marital relations with Joseph after the birth of Jesus, or did she remain a virgin her whole life? Does it matter, and if so, why?
Is it permissible to use modern medicine to treat sicknesses and injuries, or do we just pray and hope for the best?
Is euthanasia permitted under any circumstances? Is "pulling the plug" and letting someone die naturally the same thing? Should extraordinary measures be taken to keep someone alive? Is keeping someone on life-support machines or even giving them CPR or defibrillating them "messing with God's will?" Should Christians always have a "Do Not Resuscitate" order ready for them (or their families) to give to doctors, nurses, and EM Ts?
May certain drugs (for example, peyote) be used in Christian worship? May Christians use any kind of drugs outside a worship context, or no?
Are some sins worse than others, or are all sins equal in the eyes of God? Might there be mitigating circumstances? Are all sins forgiveable, or are there some that cannot be forgiven? Is there a point where it's too late for forgiveness?
Should we actively go out and preach, or simply wait for people to come with questions? Is there "a time and a place?" How important is it to "win souls for God?" Does doing so win you points for the afterlife?
Is dance appropriate for Christian worship? Should we dance at all? Are there certain kinds of dances that are not appropriate?
Do we have to get dressed up for church, or does God not care what you wear (or don't wear)?
Can we be possessed by demons? How do we know who's possessed, and who has a mental or physical illness? How might people become possessed, and is there any way to prevent it? Who can perform an exorcism?
Do children sit in the pews with their parents, or do they go to Sunday school while the adults worship? Who is considered an adult within the church?
Are people who are Driven to Suicide automatically barred from Heaven if they succeed? Or does God show compassion for what motivated them to that point? Does God even care about why someone did anything?
Are we permitted to use violence and/or weapons to defend ourselves, our loved ones, or our property? Or are we to be Actual Pacifists?
Are we obligated to obey our parents as adults, or only as children? How much (if any) say do parents get in their child's choice of mate? Do parents have the right to use corporal punishments? Should they, or is there another way?
Should parents keep their children sheltered from the world, or allow them to participate in worldly activities? Should children be educated at home, religious school only, or can they attend secular school?
Are we obligated to take our parents in when they reach old age? Can they be placed in nursing homes or assisted living facilities? If there is more than one child in a family, which one does the responsibility of elder care fall? What if they can't take that responsibility on, or are not willing to?
Do we have to go to church every Sunday? Or Saturday? Every day? Once a month? Are Christmas and Easter enough? Are there Holy Days of Obligation? Is it OK to do certain jobs on the Sabbath? What about partaking in leisurely and/or social activities?
How often do we have to receive Communion? Is that even necessary? Who can receive Communion?
Is cremation a permissible practice, or must the deceased be interred in a casket? How does that mesh with finite space on Planet Earth? What about when people die en masse, as during The Plague or a war? Will people who are cremated be able to be resurrected at the end of time?
Is it OK to verify that a needy person is actually needy, or are we to hand over money to whoever has their hand out? Should we help people directly, or can we donate through charities? Should we support social welfare programs? Is it OK or even better to help someone out in non-monetary ways?
Will our pets be able to join us in Heaven? Are animals accountable to God for the way they live? Do they have souls? Can they be considered sentient? If so, does that mean eating meat is a bad thing?
Are we permitted to attempt to communicate with the dead? Is that dangerous? What about trying to predict the future? Is it OK to read the horoscopes in the newspaper Just for Fun, or is that sinful? Do certain people have psychic abilities, and might these abilities be gifts from God? Is it OK for such people to use their abilities for good purposes?
If some people are saved, and some people are not, how do we know who is saved and who is not? How do we know what our own status is? Might that status change? Is there any point in living if you are not among the Elect?
How does the concept of Hell mesh with the concept of a loving, compassionate, and forgiving God? Is there a limit to God's forgiveness or compassion?
How does the concept of a murderer/rapist/child molester/thief/etc. being able to get into Heaven provided he/she repents mesh with the concept of a holy and just God?
Is it OK to view and worship God as the chief deity of a larger pantheon, or must the very notion of other gods be renounced?
Is Jesus meant as a "personal Savior," or did he come to help all of humanity? What does it mean to develop a relationship with Him?
Is it OK to donate ill-gotten money to the church, or is that money "contaminated?"
Are we obligated to forgive all offenses against us or people we care about? Is it bad to hold a grudge for something big? Or are some things unforgivable? Is it OK if we need time to get through our anger and hurt, or are we obligated to swallow our grief and forgive instantaneously? Does forgiving someone mean we are obligated to be friends with them? Is there such a thing as righteous or justified anger? Can parents disown their children?
Do we as humans have the right to bargain with God? Do certain humans have that right and not others? Is God's will flexible, or is it set in stone?
Should our religious beliefs have any influence on who we vote for? Should we be living in The Theocracy?
Is it OK to listen to secular music, read secular books, watch secular TV, etc?
Are we obligated to confess our sins to a religious leader, or is it enough to pray privately for forgiveness? How often should we do it? If we confess, is that confidential? Or can the person who hears confessions report what they heard, such as to police?
Can you be a good person without believing in God? Can people from other faiths be considered good, or do they have to convert first?
Does the Bible contain a solution or a commentary on every conceivable problem one might face, or are there issues we face in modern times that wouldn't have come up at the time it was written?
What does it mean to dress modestly? Covering up most of the body? How high can hems be? How short can sleeves be? How low can necklines be? Or does it mean keeping clothing and other adornment simple? What does that mean?
Are we accountable to God for minor mistakes? Are mistakes distinct from sins? Can you commit a sin by mistake?
Are we obligated to help impoverished people worldwide, or is it enough to take care of local problems?
Are we obligated to fast during Lent and such? Or is that voluntary? Are certain people, such as the elderly, the sick, children, or pregnant women excused if it's normally obligatory? Does it mean abstaining from any food, or simply eating less? What does fasting do for us on a spiritual level?
Does God have a certain race or ethnic group ordained as "chosen people?" Who are they? Can there be more than one? Does it even make a difference in this day and age? What about intermarriage?
If a Christian chooses to marry a non-Christian, are their children Christian by default? Does it depend on the couple's choice? Must they be raised in the faith, or can they choose for themselves later? What holidays do they celebrate, and how? Does the non-Christian have to convert for the marriage to be valid? Should they? What if the marriage doesn't work out? Should Christians avoid this problem entirely by marrying only other Christians? If "winning souls" is important, is interfaith dating/marriage an appropriate means to that end?
Is it more important to believe the "right" things, or to do good things? Or both?
Are natural disasters and wars "acts of God," or just random events? Can they be both? If they are acts of God, what purpose do they serve? Are they The Scourge of God? Can they be prevented by prayer and/or doing right? Is there any such thing as a random event or a coincidence, or does everything happen for a reason?
Could other religions be just another way of understanding and worshipping God, and therefore not "wrong," but "different?" Or is Christianity the only way to go? And if it is...then what kind?
In other words, pretty much everything is up for debate.
There are a lot of different denominations, all with their own slightly different beliefs, practices, tropes, and what not. Broken up by type:
We're going to define the Catholicism type as Churches in communion with the Roman Catholic Church as well as those churches that broke off recently, as in the last couple centuries.
Roman Catholic Church
The largest sect in raw numbers (about one in six human beings are Catholic) and one of the oldest types of Christianity, having coalesced in the 4th century AD after the Roman government began allowing Christians to practice openly. The leader of the Catholic Church, the Pope, is the Bishop of Rome just as St. Peter was; in practice, the real authority of the Church is with its Bishops, each of whom is responsible for passing on the teachings of the church intact within their dioceses. It should be kept in mind that Catholicism is comprised of diverse segments of believers and that inevitably, there's bound to be some arguments amongst themselves, and let's leave it at that.
Catholicism is generally best known for its rituals and a rather authoritarian approach to religious and moral doctrine. It is believed that the church's teachings on these subjects are "infallible" — without error — because the Holy Spirit will not allow the Church to be in error; debate remains, however on how to interpret this infallibility. There are three sources of infallible teachings, two of which are not controversial. First, there is the "Magisterium" of the Church: the teachings of the church that are considered universal by the Pope and Bishops. Second are the teachings of Church Councils — meetings of all the bishops within the Church, called by the Pope to settle in a democratic fashion questions of an extraordinary nature. The Catholic Church recognizes 21 Councils as having occurred in its history, the most recent of which was the Second Vatican Council held from 1962-1965 (which, among many other changes, allowed Mass to be said in languages other than Latin).
The last source, and the most controversial, is the Pope himself. Catholics believe the Pope is infallible when he speaks on matters of faith or morals, leaving no wiggle room. This circumstance is known as ex cathedra, which literally means "from the chair." When the Pope solemnly defines a doctrine or dogma, he is speaking ex cathedra. In the grand scheme of the Church it is a very new idea, first officially pronounced in 1870, and which modern theologians recognize as having been exercised only seven times in the history of the church, most recently in 1950. Each of the seven times, the declaration has been about rather high-level theological issues surrounding the nature of Christ and salvationnote Two are letters which define Christ as having two natures and two wills (fairly standard Chalcedonian Christology); one says, in essence, that yes, saints are a thing and are currently with God in Heaven (which is almost parodically Catholic); two denounce as heretical the points on salvation made by a seventeenth-century Flemish bishop and theologian named Jansen that amount to a program for turning Catholic theology into Calvinism Lite; one defines the rather esoteric doctrine of the Immaculate Conception, whose significance ties into the nature of Original Sin and Christ's role as redeemer; and the final one formally adopted and defined the doctrine of the Assumption of Mary, which holds that the Virgin Mary was bodily taken up to Heaven at the end of her natural life, an old doctrine the Church had long generally accepted and indeed more or less shared with the Orthodox (the Pope was vague enough on the point that the Orthodox doctrine is one of several valid interpretations of the Catholic one). rather than some specific moral or practical question.
Many people debate just how solemnly, and what language a pope has to speak to be doing so. However, if the term anathema (a bad thing, as in "let him be anathema") shows up, you're probably in ex cathedra territory. As a note, infallibility has nothing to do with impeccability, or sinlessness (Peter the Apostle, considered to be the first Pope by Catholics, denied Christ three times in The Bible).
Infallibility is viewed as a negative power, meaning that the Pope is incapable of speaking falsely when speaking ex cathedra on faith and morals. This does not extend to private letters, most public discourses, theological musings and what not, though they are to be accorded respect. Note that due to the principle of doctrinal development in Catholicism (the belief that new dogmas are simply existing beliefs that have been better understood and now explicitly defined, as opposed to doctrinal innovation, which means coming up with new doctrine or changing existing ones), this rule applies retroactively. But in practice, infallible teachings from the Pope are very rare; the Church doesn't keep an official list, but as noted above, there have been only seven in the Church's 2000-year history (of which one, in 1950, has occurred since the First Vatican Council formally enunciated the doctrine).
Catholicism recognizes seven "sacraments," signs of God's grace: Baptism, Communion (a remembrance of the Last Supper, and where Catholics believe Jesus acting through the priest turns the bread and wine into Himself), Confirmation (when people choose to become full members of the Church as adults), Marriage, Holy Orders (where clergy take their vows), Reconciliation (the act of confessing one's sins and performing penance for them, typically in the form of prayer), and Anointing of the Sick (sometimes, and not quite correctly, called "Last Rites"; Last Rites often includes the sacraments Anointing of the Sick and Reconciliation, but is not itself a sacrament). An important difference between Catholicism and some Protestant sects is that Catholics do not believe the Bible is entirely literal, only "divinely inspired." For example, Popes have endorsed the theory of evolution as both plausible and consistent with Catholic teaching, referring to the Creation story of Genesis as a metaphor or a poetic way of describing the creation of man by God. This reflects the greater emphasis that Catholicism puts on human reason and philosophy in terms of theological learning. Scholasticism, popularized by St. Thomas Aquinas, is a major influence on this way of thinking.
Another important Catholic tradition is the remembrance of Canonical Saints: people who have been found by the Church to have led holy lives, are considered examples for Catholics to follow, and are believed to have demonstrated they are in Heaven and have God's favor by granting what the church considers miracles (usually, healings without a certain medical explanation) to those who ask saints to "intercede" for them with God. There are at least 5,000 Canonical Saints (the most important being "The Virgin" Mary, who was Jesus' earthly mother), though some of them may be more legends than real people. Note that the word "saint" is often misinterpreted to mean an especially good person. In Catholic theology, anyone currently in heaven is a "saint" (hence the fact that the Church does not Canonize living people); thus, anyone who died in a state of grace is a saint, regardless of what sort life they led. When people talk about "saints", they usually mean Canonical Saints. When the Catholic Church formally declares that someone is a saint, that person is said to be "canonized", and someone who has been canonized is a Canonical Saint. Whether someone has been canonized, however, is irrelevant to whether they are a saint. The process of canonization is long and involved, with four stages. The first is "Servant of God," which is basically an official statement that "this person was very good in life and could very well be in Heaven, but we need more time to investigate"; the second stage "Venerable", which amounts to saying "this person was good enough in life that it's fairly likely he/she is in Heaven, although we have no proof"; Beatification (entitling the beatificee to the title "Blessed") after the attribution of one miracle to the deceased's intercession, meaning "We now have strong but not incontrovertible evidence that this person is actually in Heaven"; and Canonization, after the attribution of a second miracle (roughly equivalent to saying "OK now there are two miracles; either this person's in Heaven or the Church collectively is a monkey's uncle"). Thus despite common usage, the Pope does not "make" people saints; only God can do that. The Pope is merely reporting on current events.
In 1964, the Second Vatican Council announced a number of major reforms in Catholic practice, including the removal of a number of traditional saints from the (universal) feast calendar, the de-emphasizing of meatless Fridays (except during Lent) to the horror of fish sellers, nuns' habits (the full habit is no longer mandatory, just the headscarves), and the adoption of a Mass that may permissibly said in the vernacular as opposed to Latin, and issued a full repudiation of anti-Semitism, the idea that the Jews were responsible for the death of Jesus, and the doctrine that the Catholic Church was the only source of Christian salvation. Some of these changes proved quite controversial, though a modified version of the Latin Mass could still be said if you filled out the right paperwork (Pope Benedict XVI, who was known for being quite conservative, has made the process a little bit easier — technically, there doesn't need to be actual paperwork, just a steady, willing congregation and a priest who knows what he's doing). A small group of traditional Catholics continue to observe these pre-Vatican II practices of the Church.
Traditional Catholics in irregular Canonical situation
A number of conservative Catholic groups chose to reject Vatican II or some parts of it, and continue to this day to observe pre-Vatican II practice without Rome's blessing. Pope Benedict XVI made efforts to reconcile these groups with the Church, most notably making it easier to say the Latin Mass, though a full reconciliation is unlikely in the near future. A famous group was led by French Archbishop Marcel Lefebvre, becoming known as the Society of St. Pius X. A flap emerged in 2009 when Benedict XVI lifted the excommunications of several bishops Lefebvre had ordained twenty years prior (ordination without papal approval being grounds for excommunication), it having not been widely known before then that one of them questions the numbers of Holocauts victims. On the very fringes of traditional Catholicism are the Sedevacantists (sede vacante meaning the chair is empty) who claim that there hasn't been a validly elected Pope since John XXIII, and the Conclavists (who choose to elect their own Pope instead).
Actor/director Mel Gibson was one of the best known of Traditionalists with questionable standing with Rome.
Old Catholic Church
Which split off at the First Vatican Council, primarily because of their opposition to the dogma of Papal Infallibility. Funnily enough, despite their name, their beliefs are among the most liberal of the Christian denominations.
Polish National Catholics
An American offshoot, annoyed by the predominance of Irish immigrants in the American Catholic hierarchy, they joined the Old Catholic Church, but not to be outdone, then broke off with the Old Catholic Church over ordination of women.
A group of autonomous "particular Churches" of the Eastern traditions that are in full communion with Rome and recognize the Pope as head of the Church. Almost every Eastern Rite has a counterpart among the Eastern Orthodox and other Eastern churches, and largely keep the same traditions. They are pejoratively termed "uniates" by their counterparts that are not in communion with Rome. "Roman Catholicism" as it's commonly known in the West (you know, Latin, priestly celibacy, Mass, unleavened bread, old ladies wearing headcovers praying the Rosary in front of a statue of Mary) is actually more properly called the Latin Rite of the Catholic Church. Eastern Catholics have Divine Liturgy (not Mass) and use leavened bread at communion. Most Eastern rites don't require priests to be celibate (a discipline of the Latin Rite, not a dogma of the Catholic Church). However, unlike Eastern Rite priests and like their Latin Rite counterparts, bishops may not be married in the Eastern Rite; much like the Orthodox, much of the upper Eastern Rite hierarchy is therefore taken from the ranks of monks and monastics. Byzantine Catholics cross themselves right-to-left just like their Eastern Orthodox brethren. Among the one billion or so Catholics in the world, only about 17 million are from one of the Eastern Rites. Eastern Catholics are every bit as Catholic (in terms of being in communion with Rome) as the Latin Rite Catholics, but due to their small numbers and their more prominent Orthodox counterparts, most people (heck, most Latin Rite Catholics) don't even know that they exist.
Announced in October 2009 by Pope Benedict XVI, in the wake of the growing schism within Anglicanism regarding the ordination of openly gay priests, this is a new structure designed to accommodate those Anglicans who wish to convert to Catholicism while retaining their Anglican identity. The precise nature of the arrangement has yet to be revealed in an "Apostolic Constitution", but it is expected that it will enable the use of Anglican Liturgy and, to a degree, the retention of married clergy. Several Anglican groups have already indicated that they will accept the offer. This may eventually lead—and many Catholicizing Anglicans advocate—to the establishment of an "Anglican Catholic Church" along the lines of the Eastern Catholics, but for varying reasons (including the fact that the Anglicans are originally a Western rite and a desire not to step on the toes of the actual Anglican Communion, with whom Rome has maintained reasonably good relations of late) the Church is a little leery towards taking such a step.
Various Churches that broke with the Church in Rome a millennium ago or more (they say Rome broke with them, others see it as a clean break both ways). Many branches are in active discussion with the Catholic Church over reuniting, some almost a millennium:
Eastern Orthodox — Established as a distinct entity in 1054 when the Pope and the Patriarch of Constantinople mutually excommunicated each other (the question of who exactly broke off from whom is a millennium-old flame war, literally).note No, reallyliterally. The Byzantines fought the Catholics (and everyone else) by pumping fire on them . Similar to Catholicism in theology and practice, the Eastern Orthodox Church is a collection of related churches, usually of an ethnic or cultural makeup. Whatever language this group traditionally used is the language of their religious ceremonies (as Latin was for the Roman Catholic Church until recently). The main triggers for the split were Papal supremacy and whether the phrase filioque (and the Son) should be inserted into the Nicene Creed, as Eastern Orthodoxy insists that it throws off the delicate balance of the Trinity's interrelationship, which they labored so hard to establish intellectually.note Some scholars now believe that the latter issue stemmed from a massive failure to communicate on both sides — to put it briefly, the Greek version of the creed used words that had slightly different nuances from their counterparts in the Latin version, which neither side was fully aware of. At least, that's what those scholars say. Other less theologically inclined scholars would argue that the split stems ultimately from the growing cultural and political division between Latin Western Europe led by Rome and Greek Eastern Europe led by Constantinople. A further divergence from Western Christianity arose during the Hesychast Controversy of the 14th century, which resulted in the official denial of absolute divine simplicity, a view held by Roman Catholics as well as most Protestants and which (ironically) is too complex to describe here.
The most commonly known churches in this group are the Greek Orthodox Church and the Russian Orthodox church. Widely known for their practice of iconography, the making of small icons that depict saints, martyrs and other holy figures. Also on a different calendar than the Western churches, so that Easter (or Pascha, rather) and related holy days don't coincide with the ones being observed around them. (Convenient when Orthodox Christmas falls after Western Christmas - can you say clearance sale?) Like Catholics, Orthodox Christians recognize seven sacraments and venerate saints, many of whom they share in common with Catholics.
Oriental Orthodox — Not to be confused with Eastern Orthodox, this is a collection of national churches structured similar to the Eastern Orthodox Church which did not accept the Council of Chalcedon (451). The Coptic (i.e. Egyptian), Ethiopian, Syrian, Indian, and Armenian Churches are examples. Catholics, Eastern Orthodox, and Protestants sometimes label them as Eutychians (who believe that the human nature of Christ was united with and overwhelmed by the divine nature), but they self-define themselves as miaphysites (who believe in one ("mia") united nature ("physis") in which the human attributes are not overwhelmed). They consider the dyophysitism of Chalcedonian Christians to be at best crypto-Nestorian. (If you didn't understand any of that, don't worry, you've got something in common with 99% of us Christians).
Much in the way that the Eastern Orthodox recognize the Patriarch of Constantinople as first among equals, the Oriental Orthodox recognize the Patriarch of Alexandria (who confusingly lives in Cairo), the head of the Coptic Church, as the first-among-equals "head" of the communion. Despite the style "Pope" (which actually predates the Roman use of the term by 300 years) he actually has no authority over the rest of the churches (merely influence). The current Coptic Pope, Theorodos II, is 118th in a line originating with St. Mark himself.
Churches of the East — Technically Three Churches:
Assyrian Church of the East — On its own since 424, that while traditionally based in Mesopotamia it's expanded all over the world.
Ancient Church of the East — Split off from the above over reforms in 1964, based in Baghdad.
Chaldean Catholic Church — Technically a Rite in the Catholic Church that would fall under eastern Catholicism above, this church left the Assyrian Church of the East in 1553 to join the Roman Church.
Not one sect, but an umbrella term for hundreds of churches who broke with Catholicism, most of them claiming descent from Martin Luther's stand in 1521. Protestantism eschews most Catholic sacraments and the veneration of saints, and encourages individual study of Scripture. Generally, Protestants do not practice the sacraments of confession, confirmation (though in churches that practice adult baptism the ceremony shares commonalities with confirmation), or anointing of the sick. Baptism is performed by many Protestant groups, though when (birth vs. joining the church as an adult) and how (sprinkling vs. full immersion) differs from church to church. Frequency of celebrating Communion varies greatly within Protestant denominations, anywhere from never to being practiced during every service. Typically, churches with more formal liturgy (orders of service) and more Catholic trappings will celebrate it more frequently, while those lacking such liturgy will usually celebrate it infrequently and usually on an informal basis. Belief in transsubstantiation is almost unknown, but liturgical churches typically believe in a doctrine of Real Presence that is extremely similar. Around half of Protestants, by population, are members of churches that confess a doctrine of Real Presence.
Due to Protestantism's distrust of having an official hierarchy to maintain orthodoxy and emphasis on biblical interpretation, the original sect from the Reformation splintered very quickly. Protestant churches now include Lutherans, Baptists, Pentecostals, Presbyterians, and Methodists, among many others. If a sect of Christianity doesn't fall into any other category, it usually gets filed under Protestantism.
Despite the chaos of Protestant denominations, there are some useful ways to group them, arising out of their structure and doctrines. Thus general, one can categorize Protestant churches along two axes: church polity and doctrinal soteriology.
Polity refers to the structure of the denomination: i.e. how the church is organized and how it handles its internal affairs. Broadly speaking, there are three kinds of church polity:
Episcopal polity: Not to be confused with the Episcopalian denomination. This polity is hierarchal, and broadly similar to that which exists in the Catholic and Orthodox tradition. It is built on bishops (episcopos="bishop" in Greek): if a denomination has bishops, it's a fair bet that it has an episcopal polity. Bishops are ordained and consecrated church leaders, generally claiming Apostolic Succession in the same way that Catholic and Orthodox bishops do: that is to say, they were consecrated by a bishop who was consecrated by a bishop who was consecrated by a bishop, etc., etc., etc., up until one of the Twelve Apostles. Protestant churches with an episcopal structure generally have a somewhat flatter structure than Catholicism and Orthodoxy; there are usually archbishops, but no popes, cardinals, or patriarchs. Usually, a synod or assembly of the bishops of the denomination determines doctrinal issues and appoints/elects new bishops and promotes existing bishops to higher positions (e.g. archbishop) to run the day-to-day operations of the whole denomination or a large chunk of it. Each bishop is responsible for the day-to-day operations of his/her diocese (diocese="church organization within a particular territory, run by a bishop"), and it is the bishop who appoints parish priests and so on.
Presbyterian polity: Not to be confused with the Presbyterian denomination. This polity is essentially a federal democracy. Each individual congregation (i.e. local group of worshipers) elects a "session" of presbyters or elders ("presbyter"="elder" in Greek), roughly equivalent to a town council or corporate board of directors, and they handle the running of the congregation, including the hiring and firing of the congregation's minister. Congregations are grouped, usually regionally, to form a presbytery; each congregation sends one elder and its minister to join some other divines (e.g. theological college profs) to form the presbytery, whose duties typically include such things as ordaining ministers. Presbyteries can also be grouped into synods, and all of a country's synods are typically grouped into a General Assembly; these higher bodies generally have authority to determine Church doctrine and maintain Church discipline.
Congregational polity: Not to be confused with the Congregationalist denomination. This denomination runs on the theory that each congregation is its own church and can do what it likes. As in a presbyterian congregation, a board or some such body of congregation members is elected to run the affairs of the congregation. However, there is no higher authority than that board. Congregational churches can and do enter into networks with other congregations with whom they agree, but they do not need to do so, are not bound by decisions taken by the governing bodies of those networks, and may change their affiliation or abandon all affiliations at any time.
Soteriology is the theory of salvation: how does Jesus save the human soul? And which human souls does He save? This was one of the major points of contention between the Reformers and the Catholic hierarchy during the Reformation, and the reformers all came up with different theories for why the Church was wrong, and as a result they ended up arguing with each other at least as much as they argued with Rome.
Calvinism: A soteorological theory first developed by Huldrych Zwingli, a contemporary of Luther. Promoted and refined by John Calvin in Switzerland and John Knox in Scotland. Built on three points: unconditional election, limited atonement and irresistible grace. Unconditional election means that everybody going to Heaven has already been pre-ordained as such; no-one can "earn" the right regardless of their faith or good deed, in a way. This all ties into another central Calvinist doctrine, Total Depravity, which states that all men were born totally corrupted and wicked (In Adam's Fall, we sin'd all), and so they cannot love God or do Good because they are so completely evil, therefore God grants a select few irresitable grace, which cannot be rejected, and is enough to make them goody-two-shoe Christian people. With that in mind, it is God alone who knows who the Elect are. Calvinists believe in "double-predestination"; people are predestined to either heaven or hell.\\ The fundamental tenets of Calvinist doctrine, sometimes called "the Five Points", can thus be remembered by the pneumonic device "TULIP": Total depravity, Unconditional election, Limited Atonement, Irresistible grace, and Perseverance of the saints.
This emphasis on pre-ordination and the idea that God has planned (or simply knows) everything also leads into another Calvinist belief, namely that everyone has their own role or job to do on Earth, whether that be an occupation, a calling, service or whatever. This particular belief is what Max Weber termed the "Protestant Ethic", which emphasises hard work, obedience and productivity.
Arminianism: A response to Calvinism developed by Jacobus Arminius, it holds that election to salvation is conditional and that God's grace can be resisted. Many Anglicans, Methodists, Baptists, Evangelicals, and Pentecostals (see below) hold to Arminian soteriology. "Arminian" is often misspelled "Armenian," which is a totally unrelated ethnic group that has a totally unrelated form of Christianity (see "Oriental Orthodox" above). Critics of Arminianism claim it promotes the notion that one can "choose to be saved", or that one can "save themselves". Arminians deny these accusations, saying the critics are actually describing semi-Pelagianism.
These are the two major soteriological streams in Protestantism. There are others: Luther had his own soteriology, roughly halfway between the Calvinist and Arminian (although it predates the Arminian, Luther having been dead for about ten years by the time Arminius was born), which only the Lutherans really buy. Then there's Universalism, which is, simply put, "everyone is saved"; a few churches have bought into that over time. And then there's the aforementioned (semi)-Pelagianism, in which being saved is a choice you make; this doctrine would be more or less not worth mentioning, except that Mormonism (whose place in the Christian tradition is peculiar and a bit uncomfortable) has been described by a (somewhat eccentric) Mormon theologian as having a "completely Pelagian" soteriology.
Anglicanism — An offshoot of Roman Catholicism originating in 1534 when Henry VIII claimed dominion over the English church with the Act of Supremacy. Largely identical to Catholicism in terms of ceremonial practice. The sacrament of Confession is not practiced, but Confirmation is. It should be noted that Anglicanism is considered a Protestant church in a historical context; as the acceptance of the Pope as temporal head of the church is required for conciliation with the Roman Catholic denomination, Anglicans by definition are not RC. However, it did not split from Rome in the same way as the original Protestant Movement, though Henry's schism with Rome allowed many sincere Protestants within England to preach. As a result, Anglicanism is episcopal in polity; its soteriology is neither Arminian nor Calvinist nor any of those other things, but rather essentially Catholic, with a few Lutheran-inspired modifications (honestly, the Anglicans never got what the fuss over soteriology was). Further note that many "low" Anglican churches are firmly committed to independence from Rome.
Some "highs", on the other hand, are "More Roman than Rome" in terms of worship practice. Anglican Churches recognize two sacraments, Baptism and the Eucharist, as primary, since those were the only two that Jesus himself presided over. Anglicans on the whole believe in the real presence of Christ in communion, though it is officially left a mystery just how that looks.
Within Protestantism generally, belief in the Real Presence of Christ in Communion tends to be less common the "lower" the church. This is not, however, the case in Anglicanism for rather peculiar reasons. The Anglican church uses its Book of Common Prayer as its "rule of faith." This includes the "39 Articles," which are basic statements of doctrine. These state that the bread and wine actually "partake" in the body and blood of Christ. Generally speaking, high church Anglicans consider the "39 Articles" to be of historical but not doctrinal interest, but due to their closeness to Catholics they do affirm the presence of Christ in the Eucharist. Low church Anglicans, on the other hand, take the 39 articles seriously and so they also believe in the Real Presence of Christ in Communion. Likewise, it also specifies the various necessary services (daily prayer, sunday services, weddings, funerals, etc.) as well as the set readings from the Old and New Testaments as well as Psalms.
Episcopalianism: What the Anglican Church morphed into in the United States. It's not company-owned, but it's certainly the largest (and first) franchisee. The split came after the American Revolution when clergy swearing an oath of loyalty to the British monarch suddenly became a bit of a problem. Similar to Modern-Day Catholicism, albeit more liberal. Subject to the Archbishop of Canterbury (an Anglican bishop) in a "First amongst equals" sort of way, and thereby subject to the authority of the Anglican Communion as well. However, Episcopalians are not, technically, Church of England, and are therefore not subject to Her Majesty. Still keeps rituals the Catholic church has abandoned, such as incense and kneeling rails at the altar to receive communion. Like the Church of England uses the Book of Common Prayer, but with its own set of revisions, the most notable being the development of alternate rites for Sunday service with more modern language introduced in 1979.
Sadly, the Episcopal Church in the United States has been experiencing schisms lately, particularly over the issue of ordaining gay clergy, the uniqueness of Christ, and the authority of scripture (this is probably where the stereotype of Episcopalians as "anything goes" types comes from). The actual "falling apart" piece of the Episcopalian Church is a rather small number of very vocal churches. That said, several other pastors have issues with the church, just not enough to break off. Furthermore, one could argue that the Episcopalian Church has been "breaking apart" for the better part of the 20th century, with issues including abortion, gay marriage, ordination of women and so forth causing certain churches to break off. A small group of these churches have petitioned the Anglican Communion to become a separate region of the Communion within the United States (these regions are normally defined by geography, not belief). The issue is complicated.
Continuing Anglican/Traditional Anglican: The aforementioned offshoots, more religiously (though not necessarily politically) conservative than the Episcopal Church.
Reformed Episcopal Church: Broke off long before (1873) other Episcopal Offshoots. They are usually not counted with "Continuing Anglicanism" due to the breakoff being over the belief that the Episcopal Church was becoming too Catholic rather than too Liberal.
Fundamentalism — A movement within conservative Christianity unique to America beginning in the early 20th century as a response to modernity and theological liberalism. It has a heavy focus on Dispensational Premillennialism (a belief in an imminent rapture, the rapid decline of the world, the belief that ethnic Jews remain God's favored and Chosen people, and that national Israel — rather than the Church — is God's primary focus in history). Dispensationalism is a doctrine developed in the 1830s by Anglican theologian John Nelson Darby, and popularized by the widespread circulation of the Scofield Reference Bible (1909 - rev. 1917). This theology was woven into the fabric of fundamentalism and remains a key feature of much of evangelicalism to this day. Both Fundamentalism and Evangelicalism are highly Arminian.
Evangelical Christianity — Somewhat synonymous to "Fundamentalism", without the combativeness and reclusiveness of the former. While early leaders of this movement shunned mainline churches, their followers instead stayed within their congregations and spread their teachings through these communities, injecting a particular flavor of Premillenialist theology into already-existing American Protestanism. However, around the turn of the century the movement did start splitting from these mainline churches to create their own congregations and are now mostly associated with giant cross-denominational mega-churches.
Evangelicals emphasize the potential imminence of Judgment Day and the importance of converting non-believers. Notable evangelical preachers of the 20th century include Jimmy Swaggart, Oral Roberts, Billy Graham (and later his son Franklin), Jerry Falwell, and Pat Robertson. Most of these preachers are best known to the public through TV programs connected to their respective churches, and are thus sometimes called "televangelists". Evangelicals have a reputation for being highly, but not exclusively, conservative and in America are highly influential in politics, especially in the southern states.
Pentecostal/Charismatic — Another branch of Protestantism that was born in America, this refers to Christians that believe in the continuance to the present day of miraculous "Gifts of the [Holy] Spirit" mentioned in Acts and the Pauline Epistles. The gifts tend to materialize in the form of "speaking in tongues" (must be seen to be believed), faith-healing, or having the entire congregation spontaneously fall over in religious ecstasy. Needless to say, services can be noisy and emotional affairs. However, beliefs differ depending on which church type you go to. More traditional Pentecostal churches have interesting/old fashioned rules such as female church members not being allowed to wear pants due to them supposedly being too revealing. Also, traditional members are not allowed to listen to non-Christian music, watch movies or TV, or read non-Christian novels. As one can imagine, younger members are likely to sneak in "taboo" entertainment behind their parents' backs. However, the larger Pentecostal denominations such as Assemblies of God churches allow most things traditional Southern Pentecostal churches do not, but still have most of the same views on morality.
Pentecostal churches split from mainline Protestant churches around the same time the Evangelical/Fundamentalist movement did, but for different reasons. Pentecostals wanted to rediscover the emotional catharsis that was present in American Christianity around the 18th century, and Evangelicals instead sought to attack new ideas of Modernity (Darwinism, changes in social behavior, and the introduction of liberal theology). A lot of people tend to get them confused, and there is some overlap between the two movements in the modern day, particularly with the more visible televangelists.
Pentecostal churches are almost invariably congregational in polity. Pentecostal soteriology remains highly Arminian in North America, but is decidedly Calvinist in other places, like South Korea.
Lutherans — A collection of predominantly Germanic and Scandanavian denominations that broke communion with Rome under the leadership of Martin Luther. The most important issues were salvation by faith alone, the total bondage of the will to sin, and scripture as the only infallible authority. Believe in the objective presence of Christ in communion (but in a different way than Catholics. Catholics believe in "transubstantiation", or that the bread and wine become the actual body and blood of Christ. Lutherans believe in "consubstantiation", which teaches that Jesus is real and present in the meal, but doesn't necessarily specify in what way). Unusual among Protestants for their identification of being 'born again' with baptism. Episcopal in polity; their services are very similar to Catholic masses. Much like the Anglicans, they have a split between catholicizing "high church" and reforming "low church", although none of the catholicizers are quite as high-church as the Anglican ones. Originally known as 'Evangelicals.' They only recognize the sacraments of Baptism and the Eucharist. Lutherans believe that people are predestined to heaven, but not to hell. Lutherans reject dispensationalist theology.
Methodists — Offshoot of Anglicanism started by John Wesley in Britain, this movement focused on holiness, pietism, and Christian Perfection. Wesleyan Methodism is very Arminian as a whole, although his colleague George Whitefield was a Calvinist. In polity, Methodism is episcopal, albeit without a strong emphasis on Apostolic Succession, and with a strong presbyterian influence on their structure. The modern United Methodist Church is largely Arminian in soteriology, while Methodists in Korea are decidedly Calvinist.
Reformed/Presbyterians: As the name implies, these have a presbyterian polity; also, following the Reformed tradition of Zwingli, Calvin, and Knox, they typically have a Calvinist soteriology. The major origin point for this denomination is Geneva, but most extant churches originate in either the Netherlands (where the Reformed church became dominant for a number of reasons) or Scotland (where Knox successfully converted the Lowlands). In general, if a church calls itself Reformed, it's probably in the Dutch tradition, while if it calls itself Presbyterian, its probably in the Scottish tradition.
Zwingli believed that communion is symbolic, but Calvinists (following their namesake) believe Jesus is "pneumatically" present.
Baptists — Baptists are defined from other Christian sects by practicing baptism when one becomes a Christian, rather than infant baptism. Baptists reject the Nicene, Apostle's, and Athanasian creeds — electing to accept "no Creed but the Bible". The Southern Baptist denomination is centered in the American Deep South, where it is a deeply ingrained part of traditional Southern culture, and often characterized as an exceedingly conservative organization and an important part of the community, especially in rural areas. Other Baptist churches and subdenominations vary widely in actual doctrine, often adhering closely to one of the other denominations mentioned on this page. Baptist churches are nigh-universally congregationalist in polity; many Baptists adhered to slightly modified Calvinist soteriology.
Anabaptists — an extreme Reformation sect that practiced an extreme heresy in the eyes of the rest of the rest of Christianity: "believer's baptism," a re-baptism for people when they join the church, regardless of whether they were baptized as infants. In fact, Anabaptists didn't believe in baptizing infants at all. This ended up going badly for the Anabaptists; it turns out that infant baptism is the kind of issue that makes strange bedfellows. In between killing each other, the Roman Catholics and the Lutherans teamed up to burn and drown the Anabaptists on this issue... Didn't really work, as the existence of modern day Amish and Mennonites can attest.
A lot of moderen Anabaptist descendants believe in nonviolence and separation from modern societies and countries. Anabaptists are not to be confused with Baptists, which are descended from more "mainline" Protestantism. Anabaptists are survived in the modern day by a number of different denominations, including the Amish, Mennonites, and Hutterites. These groups tend to be almost exclusively based in rural communities, though there are plenty of exceptions. To qualify the rosy portrait given above, it must be noted that many Anabaptists were violent theocrats. Incidentally, the Mennonites (from whom the Amish split in the 17th century) were always pacifists and separatists, which was the reason they survived persecution, not a result of persecution.
Amish — Probably the most well known of the Anabaptists, they are most well known for their disavowal of technology. They aren't hostile to technology per se, only its tendency to get in the way of leading a good Christian life. So they do allow Schizo Tech — case in point: horse drawn buggies with blinkers. Also famous for their barn raisings, quilts, excellent homemade furniture and oddly enough, wild teenagers. They are also sects maniacs, schisms within schisms (based as often on what technology and/or dress is permitted as actual beliefs), to the point where many sects consist of a single congregation, and more than one of a single family. Outsiders tend to collectively refer to the horse-and-buggy, no-buttons sects as "Old Order".
On the wild teenager issue: it is referred to as Rumspringa or Rumschpringe, a method to short-circuit the "teenage rebellion" phase by giving said teens free rein to rebel for a short time (as many tropes on this site will tell you, teenagehood and strict religious moralizing are not the best combination for producing a mentally healthy adult). It also allows the teens to make an informed choice about whether or not they want to join the church by showing them the "other side of the coin". At age 16, teens are allowed to leave the Amish community and experience life outside, and unsurprisingly, the experience usually consists of a combination of Sex, Drugs and Rock & Roll. At least, that is the Hollywood version of the event. In most communities, Rumspringa tends to be quite tame. It simply involves the parents giving the teen more space to act out, be slightly more tolerant of "the lip", letting them wear "Englisch" (the Amish refer to anything and anyone "not-Amish" as English, regardless of its actual nation of origin) clothes, drive, drink alcohol, and such. The outrageous things are usually done more out of a symbolic "been there, done that" ideal then in actual defiance. The period ends when the teen is ready to return to receive baptism to join the church as an adult, or with him or her deciding to leave the church. Moral indiscretions in this period are usually quietly forgiven and forgotten. All things considered, leaving the church (which is not the same thing as getting the shunning treatment) is a very rare event. This practice also means that for a subculture that shun technology, every Amish knows how to drive.
Mennonites — Another modern day Anabaptist group, the Mennonites have much in common with the Amish, including similar beliefs (such as nonviolence, believers baptism, and the separation of church and state) and a penchant for sects and schisms. Their views on technology and interaction with the outside world are much less strict than the Amish, however, and run the gamut from complete isolation to immersion. They sometimes serve as the "Shabbat Goy" for their more restricted Amish brethren, providing services that the Amish cannot do themselves. Any two given Mennonite congregations could live drastically different lives, from communities indistinguishable from the Amish, to those who live in cities with modern technology such as cars and computers. The Mennonite Church in North America consists mostly of the latter kind of Mennonites; the conservative, Amish-looking Mennonites are a minority. Also, thanks to missionaries there are fast-growing Mennonite populations outside of North America, and Africa as a continent now has more Mennonites than North America does.
Quakers — The correct name is Religious Society of Friends. At the very core they believe that God (or Jesus, or the Light, depending on where you are and who you ask - some Quakers are non-theistic) is in everyone. From this comes a number of other, better known values, such as nonviolence (would you kill God?), simplicity (so you can better hear the light), equality (if God's in everyone...), and integrity (would you lie to God?). In consequence, they were early supporters of race, gender, and gay equality, the abolition of slavery, and nuclear disarmament. Very non-hierarchical; they do not believe in ministers and "meeting for worship" consists of any one who wants to coming up and talking about whatever they want, amid vast amounts of silence (yes it's supposed to be "awkward"). Quakers show up in some of the most unexpected places; for instance, would you believe that Richard Nixon was a Quaker? (He wasn't particularly religious, though.) (Herbert Hoover was also a Quaker.)note Interestingly, although Quakers aren't supposed to "swear" things—they're supposed to "affirm"—both Hoover and Nixon "swore" the Presidential Oath of Office. This is particularly surprising in the case of Hoover, who was otherwise quite serious about being a Quaker; his post-World War charitable work relied heavily on Quaker networks, and his general reputation for personal charity and kindness (despite his disastrous laissez-faire economic policies) are very much in the Quaker mode; it would be fair to call him the Jimmy Carter of his day.
Shakers — got their name from the fact that they'd "shake the sin out of their fingers." Founded by Ann Lee, it dwindled to a current population of 3 (yes, three) as of December 2009 due to the fact they don't believe in sex, helped along by a 1960 law that banned religious groups from adopting children. Renowned for their furniture.
Seventh-day Adventists — The basics are in the name: they worship on the Jewish Sabbath (sundown Friday to sundown Saturday) instead of on Sunday, and they believe the Second Coming is imminent. They believe that they should honor the Sabbath each week, but, like most Christian sects, do not follow the scriptural teachings of the Sabbath Year (every 7th year) or the Jubilee Year (every 25th or 50th year). Also known for vegetarianism, a strong focus on healthy living (many adherents belonging to the medical field), and a belief in soul sleep. Adventist teaching is largely based on the work of a nineteenth-century writer Ellen G. White; Adventists refer to Mrs. White as the "Voice of Prophecy" and consider her writings second in authority only to the Bible. The SDA grew out of the Millerite movement which believe that the world would end on 22nd of October 1844. This day is now referred to as "The Great Disappointment" in a massive understatement. Many modern Adventists view "The Great Disappointment" as a result of misinterpretation of the of the date, stating that it was incorrectly meant to be the end of the world, when it was merely the start of "The Remnant Church" in preparation for the End Times.
On the healthy-living front: The Seventh-Day Adventists ran numerous sanitariums in the late 19th and early 20th centuries, particularly in the Midwest (and most particularly in Michigan)—today, the SDA runs the second largest "chain" of hospitals in the US, behind the Catholic Church. While some SDA ideas did end up in modern nutrition, a lot of them (like eating bland food to suppress impure urges) didn't. They are, however, responsible for the Kellogg's food company, makers of the corn flakes you ate for breakfast this morning and a few other forms of breakfast cereal.
Stone-Campbell Restoration Movement — generally called some variant of Disciples of Christ, Church of Christ, or a generic Christian Church. Founded when Barton Stone and Thomas Campbell independently came up with the idea that all these creeds and churches named after a founder is wrong. Individual churches are autonomous and believe on full immersion baptism. Southern Churches of Christ tend to be strictly non-instrumental, while the northern Christian Churches use instruments. Disciples of Christ formally split from the others when they formed an ecumenical council.
In many cases, the independent "Christian Churches" that schismed off in the 20th Century are basically Baptists in practice, descended from Presbyterians (the Campbells were Scots-Irish), and refuse to use any sectarian name more specific than "Christian." (The term "Campbellite Baptist" was applied by outsiders, and is not used by the sect.) Quite a small sect, and of course they insist they're not a sect, they're just Christians. Very confusing, and then they start calling themselves Christian in contrast to other Christian sects, thus taking the name of a major world religion for their tiny schism of same.
Christian Scientists — more properly "The Church of Christ, Scientist." Founded by a Boston woman, Mary Baker Eddy, whose sickness was not healed by "animal magnetism" (which worked by inadvertently hypnotizing the patient) but did get better after praying. Their main difference from other types of Christianity is denying the existence of the physical world (which peculiarly sounds rather like Buddhism). This leads to the conclusion that there is no need to rely on drugs and medical treatment, since these imply a reality to the physical. In practice, failing to be good enough at seeing that there is no physical world is not a sin, so members are allowed to seek medical help as a second resort. They also deny the existence of evil, Satan, and any need to evangelize or proselytize. They are very much in favor of reading, though. Not to be confused with the Church of Scientology. The sect established The Christian Science Monitor as a response to criticism and ridicule of Eddy early on; it eventually became a top outlet for high-quality journalism in the United States.
Moravians — One of the oldest Protestant sects, and one of the very few surviving that can lay claim to independence before Martin Luther's proclamation. The Moravians have their origins in 15th century Bohemia and Moravia, following the execution of Jan Hus, a priest who openly criticized the Catholic Church, particularly their practices of indulgences and not allowing texts to be published and said in the language of the people. He was burned at the stake in 1415; his followers organized and rebelled. Although they were successful, they were eventually overrun and scattered by the Catholic Habsburgs in 1621. A group of refugees managed to escape to Germany, where an open-minded nobleman, Count Nikolaus Ludwig von Zinzendorf, allowed them to settle on his estate at Herrnhut. Fascinated by their story and teachings, he eventually became a Moravian bishop, sent forth the first Protestant missionaries, and founded the American Moravian settlements of Bethlehem, Pennsylvania and Salemnote now Winston-Salem, North Carolina.
Much like their early counterparts, modern Moravians strongly believe in a focus on the essential basics of Christianity, the freedom to choose styles of worship, tolerance towards others who believe differently, and a call of stewardship to dedicate time and talents to those who need them. The most famous Moravian practice is the Lovefeast, a simple meal, usually bread and a beverage, eaten as a congregation to show of fellowship and celebration.note This does not replace communion, which Moravians also observe. There are also 26-pointed stars called Moravian stars that are often used as Christmas decorations; they did not get their start as religious symbols, but are called so because they were used as a geometry lesson at the Moravian Boys' School in Niesky, Germany. And their Christmas cookies are awesome. The Moravians were a strong influence on John Wesley; he actually studied with Zinzendorf in Herrnhut for a brief time, though he ultimately disagreed with them on a few key theological points. These difference were enough for him to create what would become Methodism.
The following groups are pretty hard to fit into any of the above categories. Some of these sects are considered by some of the other sect to not be Christian. Most of them tend to disagree. We will all (mostly, somewhat) agree that they are definitely not Catholic, probably not Protestant, and that we really, really, really don't want to start a Flame War (literally or figuratively) about this issue.
Gnosticism — Non-"orthodox" sects which were active from approximately 100-400 AD. Orthodox Christian sects ended up disavowing them, which resulted in some rather interesting developments. Gnostic writers and their texts were far more common in the early centuries of the Church and have a very different flavor than the modern Bible. Today they are largely extinct, but a few holdouts still remain, especially with the discovery of the Nag Hammadi library in the 1940s.
Gnosticism interpreted the teachings of Christ in the context of late Greek philosophy and local polytheistic religions. Gnostics identified the God of the Old Testament with a being called the Demiurge, a kinda sorta evil deity who created the world to trap human souls in flesh. They saw Jesus as an incarnation of pure wisdom sent by a good God to teach man to transcend his bodily form, but not as a universal "savior" in whom one must believe. Though Gnosticism itself is rarely heard of outside theological symposia these days, its influence can be felt in the Gospel of John, which shares much gnostic terminology, while subverting it (John 1:1, the word, or Logos, became flesh, wah!?). Also in The Da Vinci Code, but that's another story.
Catharism/Albigensianism was a particularly large offshoot of the gnostics. Taking root in France in the 11th century, they allegedly believed in poverty, avoidance of sex, and vegetarianism (but fish and anal sex were both OK, one because of confusion about how sexual reproduction works, the other because it can't lead to having kids). They were ultimately all but wiped out during the Albigensian Crusade in the 14th century, making their final stand at the fortress of Montségur in southern France. (But not before they gave us the word buggery.) The voluntary poverty of the Dominican Order of Preachers was inspired by the Cathars, against whom Saint Dominic himself had preached with limited success. Note that as the Cathars never committed the details of their religion to paper, virtually all sources for actual Cathar beliefs are suspect, having been written by the Catholic Church, who had every reason to twist the truth and even outright lie about Cathar beliefs and practices.
Messianic Judaism — A largely American and British phenomenon beginning in the late 19th century, Messianic Judaism attempts to reconcile the division between Christianity and Judaism by combining aspects of each. Messianic Jews tend to describe themselves as Jews who observe Jewish law and believe that Jesus is the messiah as described in the Hebrew Bible. Other Jewish groups dispute their self-identification as Jews; the Law of Return in Israel, for one, considers them a separate religion.
One of the best known branches of the movement is "Jews for Jesus," which was founded by and largely consists of former Southern Baptists—although the status of "Jews for Jesus" as Messianic Jews is somewhat complex, as many of them simply convert to Baptist Christianity and continue observing some Jewish customs, rather than the full-fledged "Judaism, but we believe Jesus is the Biblical Messiah" attitude of many other Messianic Jews.
Mormonism — More properly known as "The Church of Jesus Christ of Latter-day Saints". Members of this church prefer to be referred to as LDS or Latter-day Saints, but understand that Mormon is the most generally recognized term for members of this faith. Established in the US in the 1830s by Joseph Smith, a prophet who claimed to have translated The Book of Mormon from golden tablets containing records of early migrants from the Middle East to the Americas (one group came over ca. 2200 BC, the other ca. 600 BC).
They have very different ideas of what God is compared to mainstream Christianity, since LDS doctrine holds that there was a universal departure from what was taught in Christ's time, necessitating a restoration via Joseph Smith. The LDS church holds the view that there are living prophets on the Earth today relaying modern revelation, much of which is found in the book "Doctrine and Covenants". The canon of Scripture is: the Bible (in English-speaking countries, the King James version is official), the Book of Mormon, the Doctrine and Covenants, and a smaller, more miscellaneous volume called "Pearl of Great Price". The LDS view of the afterlife includes three possible levels that can be fairly described as "heaven" (and one level called "outer darkness", reserved for the most evil). Mormons believe if they do good works and live faithful lives now, they can be Gods in the afterlife and rule over their own planets. This is not to say that they believe they can "earn" this on their own merits. They don't, but regard the Atonement made by Christ as essential to any of this and that even after becoming like gods they are still under the rule of God. (The fact that the word god has multiple meanings makes the topic somewhat confusing to talk about.)
As in any major religious group, there are offshoots of the Latter-day Saints church, some of which are the source for the continuing stereotype of isolated polygamists. The mainstream LDS church, based in Salt Lake City, Utah, considers polygamy grounds for excommunication, and has since 1890, Divine authorization for this practice having been withdrawn (largely due to Congress' insistence on a ban on polygamy before granting statehood to Utah). As Mormon doctrine is wildly different from most other Christian churches, as noted above, some don't consider it to be Christian at all. Others (such as Latter-day Saints, obviously) take the view that Latter-day Saint theology is a restoration of original Christianity, without accretions and variances found in other Christian traditions. Rather good at keeping genealogical records, incidentally, due to the doctrine that families are meant to be eternal, they believe it is possible for dead people to be converted.
Unitarian Universalists — An offshoot of 18th-century Deism, the idea that God is a "cosmic watchmaker" who created the universe, and has spent the time since years watching his Great Work unfold perfectly, while not interfering any more than a watchmaker must once the watch he builds is activated. Composed of two different denominations that merged: the Unitarians who, amongst other things, believed in the singularity of God and the non-divinity (though awesome person) of Jesus, and the Universalists, who believed that since God loves everybody, He's not going to let any of them go to hell. Currently it is the only major world religion that is either a path for finding one's own spirituality and beliefs or a church for people that don't like religion, depending on who you ask. Many Unitarians would probably not identify themselves as Christians and some might identify as Buddhists, Jews, agnostics, Wiccans, atheists, or just about anything and/or any combination imaginable. Why are they here? Because the world is weird, that's why.
There are some small unmistakably Christian Unitarian groups, maintaining the old traditions of Christian Unitarianism: that is, a combination of mild Calvinism with Deism, with Jesus being accepted as a great moral teacher and possibly the Biblical Messiah, after a (unique) fashion (they were rarely pure Deists). This wasn't particularly uncommon in the US in the 18th and 19th centuries, being a highly intellectual offshoot of standard New England Congregationalism. Four US presidents (John Adams, John Quincy Adams, Millard Fillmore, and William Howard Taft) were Unitarians in this sense (Taft actually had to fight accusations of atheism because of this, as he had been offered the presidency of then-Congregationalist Yale before he became President of the US and responded "I do not believe in the divinity of Christ" and had to explain that he meant that he was a Christian Unitarian, not an atheist). Thomas Jefferson was also a kinda-sorta Unitarian; his Christology and Deism match up, but even if he had been the churchgoing type, it would've been difficult to find a Unitarian church in Virginia (where Episcopalianism was the state religion until Jefferson himself signed the Virginia Charter of Religious Freedom in 1786, and which was not fertile country for Northeastern Congregationalisms of any kind).
Jehovah's Witnesses — Jehovah's Witnesses treat The Bible as the only source of truth. They use God's name, Jehovah, and are most widely known for their worldwide preaching activities, honoring Jesus' command to "make disciples of people of all nations." They do not consider Jesus to be God himself, but rather, the son of God and inferior to the Father. Each member of this faith has made an extensive study of the Bible and dedicated his or her life to Jehovah God to do his will. No one is required to preach for any set amount of time, nor do they receive any pay, for their witnessing is a lifelong volunteer work. Their official website, with Frequently Asked Questions and other information, can be found here.
They teach that Christ was not nailed to a "cross" but a stake, which was the common method of execution for criminals then, and which the Romans referred to as a stauros (upright stake) or crux simplex in Latin. They also believe that only 144,000 persons will reside in Heaven while the rest of the faithful will remain on earth to live forever in peace, and the wicked will be destroyed (i.e. and not spend the rest of eternity getting tortured, a view not shared by most of Christendom). Focus on individual study of the Bible, the holiness of blood (they are not OK with blood transfusions, but don't go to the lengths Jews go to to remove blood from meat), and disbelief in the ability of earthly human governments to solve the world's problems (they obey the laws of the land in which they reside and pay taxes, but refuse to serve in the military or salute the flag). They are most known for their door to door preaching work, or "witnessing" which has both changed many lives and annoyed many others. FYI: Although the late Michael Jackson used to preach door to door, he had left Jehovah's Witnesses soon after the release of Thriller. (In his immediate family, only his mother is an active member.)
Arianism — an offshoot of Christianity that sparked the first major heresy of the young religion. They believed that the Father created the Son, while the mainstream Christians believed they both always existed. Really, really big outside of The Empire and among the Germanic tribes. though it never really caught on with any group that didn't get conquered by someone else. Arianism is sometimes used to refer to believers in the creation of the Son who had no continuity with the original Arians, such as (possibly) Isaac Newton. Not, repeat, NOT to be confused with "Aryanism".
Nestorianism — The doctrine that Christ has two persons. Named after Nestorius, Archbishop of Constantinople 428-431, who taught that Mary could be referred to as 'the mother of Christ,' but not as 'the mother of God.' His opponent, Cyril of Alexandria, argued that this implied that Christ was really two persons rather than one. Nestorius was deposed by a council held at Ephesus before his supporters could arrive. Nestorianism flourished in Persia and extended as far as China and India. Most modern Nestorians hail from either Iraq or India. Notable for being the religion of many of Ghengis Khan's relatives and in-laws.
Monophysitism — The doctrine that Christ has only one nature. Divided between Eutychianism (now extinct) which taught that the human nature was overwhelmed by the divine like a drop of water in an ocean. Miaphysitism, which holds that the human nature was not thus overwhelmed, is the position of the Oriental Orthodox churches
Donatism — A sect in North Africa that split from Rome due to a controversy over the continued service of bishops and priests who had recanted Christianity while under torture. Best known for teaching that the validity of sacraments depends on the purity of the priest or bishop who administers it, concluding that if a person ever confessed to anything under torture they were unfit to be in a church position, and their association with the Circumcellion. Famously opposed by St. Augustine, who originally had doubts about calling in the Roman military to quell rebellions over the argument, as he felt calling in earthly, political authority to settle church matters might set a bad precedent for later conflicts. Hindsight is 20-20, as they say. Donatism was slowly reabsorbed into Catholicism before dwindling to nothing following Muslim occupation.
Circumcellions — Perhaps the most bizarre of them all. They decided that the primary virtue in the life of a Christian was martyrdom, and to that end, wandered the countryside with blunt clubs they called "Israelites." They would waylay armed travelers, taunting them and beating them lightly with the clubs while shouting "Laudate Deum!" in hopes of earning a swift martyrdom. They really did that. Obviously one of those sects that are universally regarded as "not getting it". Also probably got funny looks in the afterlife. This sect was wiped out in the 4th century after several groups decided to help them out and slaughtered all their members.
Christian Identity — A sect based loosely on British Israelism, a now-discredited 19th century anthropological hypothesis claiming that the Anglo-Saxon, Germanic, and Celtic peoples (i.e. modern Western/Central Europeans) were the descendants of the lost tribes of Israel. While other Christian groups concern themselves with baptism, interpretation of scripture, clerical authority, and other theological debates, Christian Identity is all about Mighty Whitey. They believe that white people are God's chosen race and the only ones capable of attaining salvation, while non-whites have no souls and thus cannot be saved. The modern Jews are descended from either Satan himself (the product of the intercourse between Eve and the serpent) or from relatively recent (last thousand years or so) converts with no connection to the ancient Israelites.note This is a sharp contrast with the original British Israelism, which was often more Judeophilic than anti-Semitic, the argument going that "if we Europeans are part of the same ethnic family as the Jews, then what reason is there for ethnic bigotry?" This sect is almost exclusively found within white nationalist and far-right political movements within the United States, including the modern Ku Klux Klan.
Positive Christianity — A sect formed by Nazi Germany in order to provide a theological fig-leaf for their rule and win over the more religious Germans. It rejected the parts of the Bible descended from Judaism, including the entire Old Testament, and retconned Jesus into a full-blooded Aryan who fought against Jewish "corruption". Largely died out after World War II, for obvious reasons, and now a quaint footnote in the history of Christianity practiced only by a tiny smattering of neo-Nazi diehards.
Muddying the waters in regards to discussions of Christianity and its various denominations and branches is that the names of some of these branches come from concepts that most of Christianity adheres to. Words such as "catholic", "orthodox", and "evangelical" have meanings beyond being the name of a kind of church.
Corrupt Church: Let's just say every church has the possibility for this, and history is filled with examples of churches going horribly wrong. The bigger the institution, the more likely it is to have rogue elements while the smaller the institution, the more likely it is to fall under the sway of one corrupt leader.
Deep South: The region is also known in North America as the Bible Belt.
Devil's Advocate: The Devil's Advocate (advocatus diaboli) is the popular name for the Promoter of the Faith (promotor fidei), a person appointed by the Catholic Church who argues against the formal recognition of someone as a Saint by, again, the Catholic Church. The job has been taken up on at least one occasion (Mother Theresa) by an outright atheist (Christopher Hitchens).
Evil Counterpart: According toThe Other Wiki, at least, some Christians believe in an evil counterpart to the Holy Trinity called the Unholy Trinity, consisting of Satan (evil counterpart to God), The Anti-Christ (evil counterpart to Jesus) and the False Prophet (evil counterpart to The Holy Spirit)
Fanon: Much of Christianity's pop culture presentation comes from the work of artists and writers of non-Canon literature, perhaps most famously John Milton and Dante Alighieri. This may explain some of the non-source weirdness in Christian belief.
The Fundamentalist: No more of a problem with Christians than with any other religious faith, but no less so, either. In particular, a bad phenomenon in recent years, as the rise of Christian Fundamentalism in America - the most powerful country in the world - has had repercussions all around the world.
God He is present in all the sects but they have disagreements on a lot of stuff.
God Is Good: Counter-intuitively, this is one of the more controversial bits of the faith to many outsiders. To almost all Christians, this may be the central point of the religion- explaining why it's so controversial.
Humans Are Special: According to Christianity, humans were made in God's image. There is also some debate among Christians if only humans have souls and can go to heaven and hell, or if animals have one as well and can go to heaven and hell.
Jesus Taboo: Obviously. Although it would be pretty hard to discuss Christianity without ever mentioning Jesus, you will sometimes find his name avoided out of reverence, such as calling him "Our Lord."
Jesus Was Way Cool: Obviously. While you don't necessarily have to be Christian to agree (as the trope page proves), if you don't like Jesus, Christianity might not be for you.
Pieces of God: Possibly the Holy Spirit. It's never clearly elaborated on, but presumably it's what allows people to perform miracles, so it may (or may not) be part of the soul. Or the soul itself.
Satan: Though the character goes back to Judaism or before, the mythology now associated with him is largely a Christian invention. His characterization has evolved continuously with the religion, growing from a rather buffoonish trickster/tempter figure in medieval folktales to an almost Manichean embodiment of evil in contemporary media. Sometimes he's been thought to represent Man's capacity to do evil, and has thus grown as our ability to do harm to one another has grown.
Saintly Church: Also what every church has the possibility to be. While there are plenty of atrocities in church history, there are also plenty of churches quietly trying to help people out. A large organization is bound to have some good elements, while a small church can have a genuinely good leader.
The Vicar: These show up in the 16th century but it's safe to say the 'funny' associations didn't come until later.
Also known for putting the Messianic in Messianic Archetype, though the trope itself is older than many of us think. The Messiah, just to let you know, is actually a Jewish Trope (and Judaism the Trope Namer). Mashiah actually means Anointed One, and refers to the King of Israel, born of David's line, who will usher in a new era of peace and restoration of the Davidic/Solomonic kingdom (the Golden Age, so to speak). Christians just happen to believe Jesus is that Messiah, whereas non-Christian Jews (obviously) don't.