Religious sects and the non-religious are not immune to this. In fact, these can often be worse than most, as dozens, hundreds, or even thousands of actual deaths are not an uncommon occurrence as a result of these arguments.

Whether or not {{God}} exists, and if so God's nature and involvement in the lives of humans is something that has been the subject of much speculation throughout history. In recent history this is often explored in "religion vs. science" debates (though the term "religion vs science" is a misnomer as, according to several surveys and varying depending on the nation, worldwide approximately four tenths of scientists are religious, another four tenths are not and the remainder are undecided. Also, scientists are human like everyone else, they still have emotions that effect them including doubt, fear and hatred, are not all-knowing and are capable of prejudice). The issue is compounded by all sides having their extremists.

Another issue is religious teachings, whether or not they apply and to what point. The disputes almost always arise from trying to get other people to share the same view or disrespecting a dissenting view, which people from all sides, religious, non-religious or irreligious have done at some point.

As a result of this RealLife subject being centered around people's deepest personal beliefs it is a sensitive topic, so please, [[RuleOfCautiousEditingJudgement be discerning when adding examples.]]
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* For every belief system, theistic and non-theistic, there are believers who are split along the lines of: "We should be prepared to compromise in order to win over new believers."/"This isn't a popularity contest, we don't budge an inch."
* ''Literature/TheBible'' is arguably the most debated religious text in real-life, also because there are teachings and events shared between Christianity, Judaism and Islam, which means the Bible is often lumped with the Talmud and the Qu'ran. One of the most debated issues is whether every word in the Bible should be taken literally and, if not, which parts are literal and which are not.
** Lumping the Talmud and the Qu'ran in the same category as the Bible also sparks the debate "is lumping them all in with the Bible for ease of categorization, showing favoritism towards Christianity or unfairly singling out Christianity for criticism?".
** There have been numerous debates over which '''version''' of ''Literature/TheBible'' should be adhered to. One example is the the King James Version vs New Living translation. Also there's the belief that KJV ''supercedes the original'' - witness (pun not intended) On the flip side you have those "enlightened" Christians who refuse to use a version of the Bible published prior to 1988.
*** Filioque. (See the other wiki [[http://en.wikipedia.org/wiki/Filioque here]]. The phrase literally means "and from the Son". The dispute is whether the Holy Spirit (the third Person of the Trinity) proceeds from the Father (the first Person of the Trinity) or from the Father and the Son (the first and second Persons of the Trinity). That's it. Yet that (together with some more political disputes) resulted in the division of Orthodox Christianity from Western Christianity.
*** There was considerable resentment that the pope introduced the -que (which had often been used in the West) without consultation.
** There's even large-scale division as to which books should be included in the canon of Scripture itself: Are the [[http://en.wikipedia.org/wiki/Biblical_apocrypha Apocrypha]] considered canonical (Catholic / Orthodox), non-inspired but still edifying (Reformers / Anglicans), or downright heretical (most other Protestants)? Was Martin Luther wantonly throwing away the books of the Bible he didn't like, or restoring it to the original version of the Jewish Rabbis and Church Fathers?
* The most debated issues in Christianity are whether Jesus was human or divine (majority consensus is He was both), who the Sacraments belong to, whether [[UsefulNotes/{{Mormonism}} Mormonism]] is Christianity and the contexts of certain verses (including whether predestination plays a role in salvation). There are also disputes over miracles, though some are merely analyses done by the clergy to determine authenticity, such as the [[https://en.wikipedia.org/wiki/Marian_apparition apparition of the BVM]].
** The East-West Schism, sparked a dispute over who was the boss among the clergy in the Church (The Bishop of Rome, i.e. the Pope vs. any archbishop of his own church), is the greatest example to be found in the history of Christianity. The differences in faith created mutual distrust between the Catholic and Orthodox churches and sparked many wars during the course of several centuries, though this was also compounded with Judaism and Islam as well.
** The series of Reformations have also caused strife as well as the denominations of Christianity. However, all denominations of Christianity draw from the same Bible and worship the same God. The differences are minor, such as Presbyterians taking cues from John Calvin and being derived from Presbyterian form of church government governed by representative assemblies of elders and Pentecostal putting special emphasis on a personal experience with God through Baptism of the Holy Spirit.
*** Examples include Martin Luther vs. Catholicism, John Calvin vs. Martin Luther, a whole bunch of guys vs. Calvin, the sectarianism. In the 17th century, Nikon, the Patriarch of the Russian Orthodox church, worked on several reforms to update the Russian liturgy to match the Greek. These reforms were protested by a group that eventually became known as the Old Believers. Although initially outlawed and persecuted, the Old Believers' religion survived and they still continue their traditional ceremonies distinct from mainstream Orthodoxy. [[note]] The reason why Martin Luther brought about Lutheranism and the Protestant Reformation is hotly debated by theologians and historians due to how corrupt the Catholic Church's clergy was at the time and his rivalry with a fellow priest over gaining a position which was a fast track to becoming a Cardinal. Whatever the motivation, Luther's ideas would have remained a mere "dispute of monks" (as [[UsefulNotes/ThePope argued by the incumbent Pope at the time]]) had it not been for the recent invention of the printing press; without the press, the only people to hear about it would be a few monks and theologians, who would proceed to write angry letters to each other until the new ideas were either accepted or forgotten. With the printing press, the public at large got wind of it within days, and that changed society forever. Of course, there were also the 95 Theses he distributed and may or may not have nailed to the door of the All Saints' Church in Wittenberg. [[/note]]
** The Second Vatican Council meeting is a point of contention for some Catholics. Though the majority who are quite comfortable with the changes to the Mass (which include saying the mass in the local language rather than Latin, the addition of a richer variety of Bible readings, the priest facing the congregation during the Mass, among others) some Catholics dislike it due to tradition while others seek a traditional Sacrameent in Latin. There is also division over some Catholics who [[SeriousBusiness believe that every Pope since John XXIII (who opened the Council) is a pretender and that the Papacy has actually been vacant since Pius XII]].
** The First Vatican Council had several Catholic groups split away from the rest of the Catholic Church over the issue of Papal Infallibility in the 19th century. It's not uncommon to find that some of these churches consist of only a handful of people; usually, the longer and more ostentatious the title, the tinier the sect (the Supreme Patriarchate of the True Apostolic Catholic Episcopalian Church of Western Europe, North America, Great Britain and All Her Overseas Dominions will invariably consist of a few dozen people at most). In terms of doctrine they can range anywhere from ultra-liberalism to ultra-conservatism, from fairly standard, if tiny Christian denominations to [[FantasticCatholicism unconventional]] [[CrystalDragonJesus hybrids]] of New Age and occultist beliefs with Catholicism. The more extreme groups tend to be obsessed with Apostolic succession [[SeriousBusiness and can (through a long complex system) trace their origins back to the mainstream Catholic Church and in theory right back to the apostles]] and have been known to excommunicate members in disputes about this. Woe betide the foolhardy person who refers to one of them as a [[BerserkButton "self-proclaimed" Bishop]] - especially since according to Catholic Canon Law these clerics are deemed to be just as validly ordained in the eyes of the Vatican as your local Catholic parish priest.
* In relation to Islam, the most prominent debate is Sunni vs. Shiite Islam.
** Ahmadiyah vs. the mainstream Islam. (Depending on the population, 'mainstream' can be Sunni or Shi'i.)
** Sufism ("esoteric") vs. mainstream ("literal") Islam.
** There's the issue of Universal caliphate vs. nationalist governments then, if nationalist, theocratic government or secular government.
** Instate Sharia as the sole law, or allow secular philosophies in law.
*** And among those advocating Sharia: Sunni or Shia? If Sunni, Hanafi, Hanbali, Maliki, or Shafi`i or something else?
** Though largely disproven now, there was also the issue of the Satanic Verses.
** Since it was formed, there is the issue whether the caliphate ISIS supports is legitimate (for the uninformed a Caliph is a person considered a religious successor to the Islamic prophet, Muhammad, or somewhat Islam's equivalent of the Pope and an overall military leader). A caliph has religious, political and military authority over all Muslims worldwide, giving ISIS a lot of power if their claim was legitimate. While most Muslims do not acknowledge their claim, there have been supporters and there is a lot of contention surrounding this which has resulted in acts of violence, oppression and terrorist attacks. The group has been designated a terrorist organisation by over 60 countries including the European Union and its member states, the United States, Australia, Russia, India, Indonesia, Israel, Turkey, Saudi Arabia, Syria, Iran and other countries.
* In regards to the Abrahamic faiths, there's the issue of if [[UsefulNotes/{{Judaism}} the Bible ends right before the New Testament]], [[UsefulNotes/{{Christianity}} the Bible ends right before the Quran]], or if [[UsefulNotes/{{Islam}} The Quran is canon too]]. And then there's contention around Literature/TheBookOfMormon. Much of world history has involved or been the result of different segments of the base arguing over where CanonDiscontinuity starts. A shared issue is whether or not gay and lesbians (in same-sex relationships) can be ordained as leaders (one case is a debate in The Uniting Church in Australia that has been occurring since 1982).
*** [[http://unsettledchristianity.com/2009/08/how-to-explain-the-religions-of-abraham-to-the-hollywood-generation/ Think of it like a movie.]] The Torah is the first one, and the New Testament the sequel. Then the Qur'an comes out, and it retcons certain key bits of the last one like it never happened. Thereís still Jesus, but heís not the main character anymore, and he didn't die but was taken up alive to Heaven (or maybe he didn't, it's not clear), and the messiah hasnít shown up yet, although Jesus will probably (it's not clear) show up again with him (or maybe the messiah ''is'' Jesus and the other guy will show up with ''him''--look, the filmmaker focused a lot on the artistry this time and put everything in rhyming verse, which while cool muddled things up a bit). Jews are fans of the first movie who ignored the sequels. Christians are fans of the first two, but the third movie doesnít count--the style was weird, even more so the production team, and the big retcons screwed not only with the canon but the fanbase as well. The Muslims are fans thinking the third one is best but appreciate the first two as well for the most part, and Mormons liked the second one so much, they started writing fanfiction that doesnít fit with ANY of the series canon.
* Buddhism - Theravada or Mahayana? Or maybe Tibetan? or Zen?
** Rinzai, Obaku or Soto Zen?
** Which Sutra? The Diamond? The Flower Sermon? One of the lesser ones?
** Is Reincarnation real or does it not matter?
*** A common question is whether it's Reincarnation or Rebirth and which one do Buddhists believe.
** Is the Buddha a God? The official doctrine in the ''Hindu'' religion that Buddha was an avatar of the god Vishnu. Official doctrine in the ''Buddhist'' religion that Buddha is not.
*** Many, probably most, Hindus came to accept Buddhist doctrine (or aspects of it) as valid, and the Brahmin priests were forced to accept that. The ''real'' controversy among Hindus when it comes to Buddhism is whether Buddhism actually counts as a separate religion, or whether Buddhists are just "Hindus in denial, going by a different name," as some Hindus have argued (needless to say, most Buddhists would be rather annoyed at this characterization).
** Is Buddhism a religion or a philosophy? Is Buddhism theistic, atheistic, or neutral?
*** Most Asian Buddhists seem to lean more towards religion, more often than not. It's often white ''Western'' Buddhists who prefer to call it a "philosophy."
** Can you be Buddhist and another religion?
*** Many people in Japan, China and the West practice Buddhism and other religions at the same time.
* If you're a Hindu, try mentioning the Kama Sutra to your pandit (that's a priest, for any non-Hindus reading this) or any fellow Hindus who happen to be elderly. They will almost definitely react in a horrified, scandalized fashion. This is due to the fact that even though Hinduism used to have much more "modern" or "liberal" (for lack of a better word) view of sex in ancient times, over the past few centuries, both conservative Muslim and Victorian British conquerors imposed a much more conservative view of sexuality after they conquered India, and this conservative view still pervades much of Hindu society today.
** The more conservative Hindu factions in India (although that's a BrokenBase in and of itself) vs. the much more liberal form of Hinduism practiced in UsefulNotes/{{Guyana}}, [[UsefulNotes/TrinidadAndTobago Trinidad]] and the other Caribbean nations with large Indian-descended populations (the British brought a ''lot'' of Indians to the Caribbean as servants). The Indian Hindus will accuse Caribbean Hindus (particularly Guyanese and Trinidadians) of "acting white", being "not Indian enough," and of being too liberal and permissive. Meanwhile, the Caribbean Hindus will accuse the Indian Hindus of being "old-fashioned," "ultra-conservative," and "too strict."
*** To clarify for non-Hindus, virtually no Caribbean Hindu practices vegetarianism unless it's a religious holiday, with the only exceptions being the priests. Caribbean Hindus typically abstain from beef or pork, but have a long culinary tradition with other meats. Caribbean Hindus also tend to have much more liberal views of sexuality than modern Indian Hindus (for the reasons why India became conservative on those issues, see the Kama Sutra entry above on this page). Finally, and this is the big one that seems to be a ''major'' BerserkButton for many Indian Hindus, Caribbean Hindus generally do ''not'' speak Hindi at all, and grow up speaking Caribbean English dialects as their native language. Hindi remains a liturgical language among Caribbean Hindus (much the same way Hebrew is for American Jews, or the way Latin used to be for the Catholic Church), but most Caribbean Hindus know only a handful of Hindi words at most. This tends to ''really'' result in [[FlameWar Flame Wars]] where Indians and Indo-Caribbeans end up at each others throats.
* The non-religious and non-theistic in general, since the only shared trait is not following a religion or believing in any god.
** There's the dispute regarding agnostics. The definition of an agnostic is someone who is unsure whether there is a god or gods. Nearly all non-believers agree there's at least some chance of god existing, but self-proclaimed atheists feel the term 'agnostic' implies a greater likelihood than they're comfortable with, much like calling themselves 'unicorn agnostics' would. Conversely, many self-proclaimed agnostics think that atheists are speculating beyond the available data: they claim that just because there is no proof of God's existence today doesn't mean there always will be none. And ''then'' there are debates over whether "agnostic" means "someone who is unsure about the existence of a god" vs. "someone who believes that it is impossible to prove whether or not any god exists." The latter definition was traditionally used, but the former definition has taken hold recently. And if you do use the latter definition, there's the issue of whether you're an "agnostic believer" or an "agnostic nonbeliever", since it's possible to believe in something even if you also believe that it's impossible to prove whether or not that thing is real. Related: There are people who seriously split hairs between "I do not believe that God exists" and "I believe that God does not exist."
*** More than that: for many, it's a conscious choice to use a term that may not be technically correct, due to an explicit desire not to be identified with strong atheists, or people who insist all of the nonreligious should be called "atheists".
*** There's also the issue of other belief systems, such as the spiritual but not religious and humanists.
** Atheism is generally accepted as a statement of belief. Atheists don't hold a belief in any gods. It has been said that getting a group of atheists to agree on something or to unite for or against something is like herding cats. Questions among those who identify as atheists is should they ever work with religious believers, against them, or both? Are all ideas fair game in the marketplace of ideas, or should atheists be sensitive to the strong attachments people might have to their beliefs?
*** Then there's the new term of anti-theists and where the distinction is, as not all atheists are hostile to religion or religious people (with some who may dislike one but not the other in both ways). There is even disputes over whether the term should be anti-theist or misotheist.
*** In addition there is much debate over whether atheists can believe in the supernatural, such as the spiritual but not religious.
** There is also the debate over whether the "New Atheists" are being Islamaphobic. This ties with the issue that prominent atheists are controversial figures, not helped by the fact that most of them are outspokenly, [[{{TheFundamentalist}} fundamentally]] anti-theist.
*** Creator/ChristopherHitchens was a very controversial person. One of the points of contention people have with him is that he claimed a religion-free society would be better (to the point of writing an anti-religion book) even after visiting a real-life anti-religious society; [[PeoplesRepublicOfTyranny North Korea]]. Hitchens' response to this criticism (which involved calling heaven a "celestial North Korea" where all you can do is praise the leader for eternity) also caused contention; some say he was absolutely right, some ([[Creator/PeterHitchens including his brother]]) say he was speculating on Heaven when he had no knowledge of it and/or that he was [[StrawmanFallacy grasping at straws]] to [[{{Misblamed}} pin the blame on religion for a problem religion didn't cause]]. His Marxist leanings in the earlier years of his career were also a point of contention. He also made the incorrect and controversial argument that the word "fascism" in the history books could be replaced with "Catholic right wing" and nothing would change. However this has been proven false for reasons including the fact that [[ConfirmationBias his claim ignores instances of non-Catholic and non-religious fascism]] including the tyrannical fascists Hideki Tōjō (Buddhist), [[UsefulNotes/IdiAmin Idi Amin]] (Muslim) and that the first fascist dictator, Benito Mussolini, was an anti-theistic atheist ([[{{Irony}} like Hitchens himself]]) [[note]]Despite Mussolini's avowed atheism and high level of contempt towards religion, especially Christianity, [[PragmaticVillainy Mussolini recognized the amount of power the Catholic Church held and sought to turn it to his own ends. This led to some actions intended to curry favor with the Catholic Church]], though Mussolini remained atheist to the day he died. The Lateran treaties that made VaticanCity a state were a response to political unrest in Italy and some of the terms served Mussolini's agenda (the Pope was pledged to perpetual neutrality in international relations and the sum the Holy See got, which they had been pledged to them by the Law of Guarantees in 1871, was reduced). Mussolini also indirectly inspired several other fascist movements such as the [[https://en.wikipedia.org/wiki/New_Guard New Guard]].[[/note]]. Hitchens also overlooked the fact that [[CriticalResearchFailure the German Fascists actually had their biggest electoral success in Protestant areas]].
*** UsefulNotes/RichardDawkins is portrayed in the media as one of the figureheads for Atheism, being part of the group unofficially dubbed 'The Four Horsemen of New Atheism' (four key figures in the movement alongside Christopher Hitchens, Daniel Dennett and Sam Harris) and certainly has a following among atheists. However a lot of people, including many atheists, find him unpleasant, arrogant, hypocritical and bigoted. A couple of the reasons for this include his Twitter post saying Islam was the world's greatest force for evil [[ComplainingAboutShowsYouDontWatch right after admitting in the same sentence that he's never read the Qu'ran]] and his hypocritical remark that [[MoralMyopia atheists should mock and be intolerant towards the religious]]. In recent years many atheists are of the opinion that Dawkins and his ilk give a bad image of atheism and the amount of atheists who ascribe to his brand of anti-theism has shrunk from the amount that the publishing of his book drew in.
*** Sam Harris, similarly, has been harshly criticized for his anti-Islamic views, which are viewed as Islamophobic and even genocidal by some (though he denies this). Other stances he has taken (such as defending ethnic profiling and torturing a suspected terrorist in a "ticking bomb" scenario) have been similarly criticized. His view that free will does not exist at all has also been a point of contention, even with his fellow "New Atheist" Daniel Dennett, who takes a more nuanced stance on the issue.
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