History UsefulNotes / HeresiesAndHeretics

Iconoclasm, as a political issue in the Byzantine Empire, lasted from around 726 to 843, with a hiatus from 787 to 814, and wound up - essentially - as a wrangle between Church and State over Imperial power over the Church (the Church won).[[note]]To give an idea of the ongoing effect: Centuries later, another emperor, Alexios I Komnenos, seized icons for their gold in the face of the simultaneous advance of the Turks from the east and Robert Guiscard's Normans from the west. The Church raised the specter of iconoclasm to drum up opposition to this move and seemed likely to raise an uproar. However, they didn't count on Alexios cleverly deflecting these accusations by being crassly materialistic about his grab: he said he had no problem with icons, it was just that the Emperor was empowered to [[IDidWhatIHadToDo do whatever was necessary--including seize holy images and other Church property--to save Christendom]]. He also distracted the Church establishment by accusing a prominent philosopher of heresy. Whether or not the icon seizure worked, it certainly didn't doom the nation; Alexios' reign marked the beginning of the last expansion of the Empire.[[/note]] Iconoclasm briefly reappeared in the initial stages of UsefulNotes/TheProtestantReformation mostly as a push back against the perceived decadence of the Catholics, but largely disappeared over the years, the only noticeable remnant being most Protestants' tendency to wear a bare cross instead of a Crucifix and building fairly austere and unadorned churches (until the High Church Anglicans decided to up the "High Church" part with the Oxford Movement, though they still don't do crucifixes as much as Catholics).[[note]]This sets aside the somewhat complicated High Church Lutheranism that formed the state religion in the post-Reformation Nordic countries and some of the German states (particularly the ones around the North Sea). It's really not worth getting into unless you have a particular fascination with Danish or Swedish history.[[/note]]

As a point of clarity, while Protestantism is in fact considered a heresy, most ''Protestants'' are not considered heretics anymore. Since, unlike the original generation, they were never Catholic in the first place, and because Protestant baptisms are not generally recognized as valid by the Catholic Church, being a Catholic heretic is rather impossible. A convert from Catholicism to Protestantism might be considered a heretic if the particular Protestant sect largely agrees on doctrine but differs on a few key points (e.g. if someone converts from Catholicism to High Church Lutheranism, which is mostly like Catholicism but still holds to the same ideas that made Luther a heretic). Additionally, the position is somewhat complicated by Anglicanism, especially as practised by the Church of England, which was originally intended as - basically - Catholicism where the Church reported to the King, UsefulNotes/HenryVIII, rather than the Pope (which, ironically, was not terribly different from how the Catholic Spain worked, only simply more overt and extreme).[[note]]Although Spain later came to be known as the workhorse of the Counter-Reformation, their church and, yes, the UsefulNotes/SpanishInquisition, reported first to the king and then to the Pope (and the latter was sometimes eschewed on the presumption the king would later report to the Pope himself). In other words, while not rejecting the Pope's authority, in Spain the church was subservient to the state and not vice versa as in many other Catholic lands of the time. This came to its biggest stretch when UsefulNotes/CharlesV bullied Pope Clement VII into kowtowing to him by literal military force, all while claiming and genuinely considering himself to be ''the'' Catholic Monarch. Clement was left so upset that his attempts to overcompensate it eventually caused the Henry VIII affair.[[/note]] Even today, the High Church part of the C of E bears a great deal of resemblance to Catholicism. The transition to a fully Protestant church under subsequent monarchs, and the according changes in doctrine, ritual, and teaching, have derailed attempts at rapprochement. The official position of the Church is that it is "both Catholic and Reformed", i.e. a Protestant church that looks and behaves Catholic. There have been movements within the Church of England to more greatly emphasize its Catholic heritage, but the clerics involved tend to either stop short of fully embracing Catholic doctrine or simply convert to Catholicism. One of those movements was the Oxford Movement, which featured the theologians such as Edward Bouverie Pusey and Creator/JohnHenryNewman. Newman himself would eventually convert to Catholicism, to the shock and outrage of the Church of England.

* Modernism -- Late 19th to early 20th century. Modernism is a theological movement spearheaded by Fr. Alfred Loisy and Fr. George Tyrell. It takes its cues from liberal Protestantism[[note]]Notably, however, most early modernists were intensely critical of liberal Protestant scholarship, and regarded themselves as an anti-Protestant tendency.[[/note]] and early modern philosophy like those of Kant and Hegel,[[note]]Though the modernists themselves would famously criticize this intellectual genealogy, insisting that they were influenced by modern trends in Biblical criticism, not philosophy[[/note]] and it teaches that the Christian faith is all based on personal religious experience, individual and collective, and under the influence of the current age. This means that the Church's dogmas can evolve over time, meaning one thing in a certain context and another thing in another. It also proposes that the Catholic Church is not divinely instituted by Christ, but rather a merely human institution formed as a means of organizing Jesus' followers. Pope St. Pius X vigorously condemned Modernism as a heresy in 1907 with the publication of the encyclical "Pascendi Dominici Gregis", a condemnation reaffirmed by Pope Paul VI in 1964. In 1966 onwards, the work of liberal theologians such as Hans Kung, Edward Schillebeeckx,[[note]]Pronounced SHIL-uh-bakes, in case you were wondering.[[/note]] and Charles Curran, was regarded with suspicion by the Church hierarchy on the basis that it represented a revival of the heresy but, while some have been censured or had their doctrines condemned, none of them have been formally regarded as heretics. The relationship between contemporary liberalism in Catholic theology and the historical heresy of modernism is one of the most divisive issues in the Church today, and implicates the boundaries of acceptable variation in Catholic teaching that are simply too complex to reproduce in their entirety here.

* And finally, all three of the Abrahamic religions "tolerate" (or not) each other to various degrees, the only thing they can agree on being their mutual distaste of polytheism. Even that is not consistent, though -- Some Christians, like the Portuguese in India, didn't mind trading with Hindus, at a time when said Hindus were largely ruled over by Muslims who rarely made any serious attempts at converting them, and there was a time where Jews didn't mind the existence of other gods so long as theirs was regarded as the top dog and the focus of worship.

As a point of clarity, while Protestantism is in fact considered a heresy, most ''Protestants'' are not considered heretics anymore. Since, unlike the original generation, they were never Catholic in the first place, and because Protestant baptisms are not generally recognized as valid by the Catholic Church, being a Catholic heretic is rather impossible. A convert from Catholicism to Protestantism might be considered a heretic if the particular Protestant sect largely agrees on doctrine but differs on a few key points (e.g. if someone converts from Catholicism to High Church Lutheranism, which is mostly like Catholicism but still holds to the same ideas that made Luther a heretic). Additionally, the position is somewhat complicated by Anglicanism, especially as practised by the Church of England, which was originally intended as - basically - Catholicism where the Church reported to the King, UsefulNotes/HenryVIII, rather than the Pope (which, ironically, was not terribly different from how the Catholic Spain worked, only simply more overt and extreme).[[note]]Although Spain later came to be known as the workhorse of the Counter-Reformation, their church and, yes, the UsefulNotes/SpanishInquisition, reported first to the king and then to the Pope (and the latter was sometimes eschewed on the presumption the king would later report to the Pope himself). In other words, while not rejecting the Pope's authority, in Spain the church was subservient to the state and not vice versa as in many other Catholic lands of the time. This came to its biggest stretch when UsefulNotes/CharlesV bullied Pope Clement VII into kowtowing to him by literal military force, all while claiming and genuinely considering himself to be ''the'' Catholic Monarch. Clement was left so upset that his attempts to overcompensate it eventually caused the Henry VIII affair.[[/note]] Even today, the High Church part of the C of E bears a great deal of resemblance to Catholicism. The transition to a fully Protestant church under subsequent monarchs, and the according changes in doctrine, ritual, and teaching, have derailed attempts at reproachment. The official position of the Church is that it is "both Catholic and Reformed", i.e. a Protestant church that looks and behaves Catholic. There have been movements within the Church of England to more greatly emphasize its Catholic heritage, but the clerics involved tend to either stop short of fully embracing Catholic doctrine or simply convert to Catholicism. One of those movements was the Oxford Movement, which featured the theologians such as Edward Bouverie Pusey and Creator/JohnHenryNewman. Newman himself would eventually convert to Catholicism, to the shock and outrage of the Church of England.

* Modernism -- Late 19th to early 20th century. Modernism is a theological movement spearheaded by Fr. Alfred Loisy and Fr. George Tyrell. It takes its cues from liberal Protestantism and early modern philosophy like those of Kant and Hegel, and it teaches that the Christian faith is all based on personal religious experience, individual and collective, and under the influence of the current age. This means that the Church's dogmas can evolve over time, meaning one thing in a certain context and another thing in another. It also proposes that the Catholic Church is not divinely instituted by Christ, but rather a merely human institution. This school of thought effectively denies the supernatural in general and divine revelation in particular. Pope St. Pius X vigorously condemned Modernism as a heresy in 1907 with the publication of the encyclical "Pascendi Dominici Gregis". In 1966 onwards, Modernism has resurfaced under the influence of theologians such as Hans Kung, Edward Schillebeeckx, and Charles Curran, denying papal and scriptural infallibility, rejecting Catholic teaching on contraception, and endorsing the ordination of women into the priesthood. These theologians have been censured by the Church and prohibited from presenting themselves as Catholic theologians.

* Feeneyism -- Quite possibly the youngest heresy on this list, and one of the few true American-born heresies, this one erupted sometime around World War II, when Fr. Leonard Feeney, a Jesuit priest, began to preach a very distorted version of the Church tenet ''extra Ecclesiam, nulla salus'', or "No salvation outside the Church." Feeney taught this to mean essentially that everyone who was not a formally baptized Catholic was, without a doubt, going to or already had gone to Hell, considered heretical due both to the Catholic teaching that it is impossible to know with certainty who is in Hell (or to declare on such matters dogmatically)[[note]]The "declare dogmatically" bit is important; a Catholic isn't breaking any rules by saying certain people are only ''probably'' in Hell, or that they believe that a person is in Hell without knowing for sure, or even saying that a person is in Hell if they were doing so--for example--only as [[Literature/TheDivineComedy part of an obvious literary device in a poem expounding on Christian principles of personal spiritual growth]] and ''totally'' not seriously suggesting that those people are actually in Hell. Right, [[Creator/DanteAlighieri Dante]]? You weren't ''seriously'' saying there are Popes in Hell, ''right''?[[/note]] and a denial of several Catholic teachings on the salvation of non-Catholics. Feeney was a notorious and vocal anti-Semite, so the implications of this doctrine, e.g., that Jews were categorically damned, were neither lost on him nor unintentional. The fact that he was also open to declaring anyone who differed with him even slightly a heretic, [[RefugeInAudacity up to and including a previous Pope, Pius IX,]] didn't exactly endear him to the church, and his interpretation of ''nulla salus'' was NOT from any magisterial authority, but from his private interpretation of Scripture.[[note]]Namely, he interpreted Mark 16 more strictly than was considered acceptable by the Church. Feeney's explanation was that the "true" doctrine had been gradually undermined by renegade clergy.[[/note]] In the end, Feeney was ordered by Pope Pius XII to knock it off and come to Rome to explain himself, and when he refused, he was dismissed from the Jesuits in 1949 and ultimately excommunicated in 1953, an excommunication only lifted as recently as 1972.[[note]]The fact that the excommunication was lifted without a recantation is sometimes used by Feeney's fans as a justification for supporting this view. Needless to say, that's not how excommunication works, and Feeneyism has been consistently condemned by the Church since then. Ironically, the rescinding of the excommunication was probably motivated by a desire not to have an aging priest be denied the final sacraments just for being a stubborn ass, meaning Feeney was a recipient of the mercy he militantly attempted to deny to others.[[/note]]

* "Galileo was famously tried before a court for an issue regarding the veracity of heliocentrism" is about as neutral as the pop-cultural understanding of the actual sequence of events is likely to get; most people seem to think Galileo was declared a heretic, or maybe even tortured for it. Let's start with the context:

The issue was that proponents of heliocentrism were unable to counter the strongest argument against it, which had been proposed by ''Aristotle himself''--if heliocentrism were true, there should be observable parallax shifts in the position of the stars as the Earth moved. Now, there ''are'' observable parallax shifts, but the technology to demonstrate that wouldn't be developed until the 18th century--decades after Galileo's death.[[note]]The distance between the stars is several light-years, very large in comparison to Earth's orbit, with a diameter of about 16.6 light-'''minutes'''[[/note]]. Until that point, the evidence suggested that the stars' positions were fixed relative to the Earth, and thus, only the Sun, Moon, and other planets were moving. Copernicus' (correct) explanation that the stars were too far away to exhibit visible parallax was not accepted, even by non-geocentrists like Tycho Brahe. Scientists back then, more used to the smaller-sized universe proposed by Aristotle and Plato, fundamentally had trouble wrapping their heads around the great size and vast distances between celestial objects needed to accommodate a heliocentric universe[[note]]Which themselves are minuscule compared to the gargantuan size and mind-numbingly vast distances of the actual universe described by modern astronomy and cosmology, but let's not get ahead of ourselves[[/note]] and proposed a "geoheliocentric" system in which the Sun, Moon, and stars revolved around a stationary Earth, while almost everything else either revolved around the Sun or revolved around something that revolved around the Sun. This system "worked" inasmuch as it didn't contradict the observed evidence (until the parallax shifts were observed), but was criticized for being more complicated and less elegant than pure heliocentrism. Galileo adopted this critique, but tried to remain restrained in his opinions in the letter to the duchess. However, being a bullheaded and rather stubborn sort of fellow, Galileo later doubled down on heliocentrism, and ''that'' got him in trouble.

** Unfortunately for Galileo, as we said above, he doubled down on heliocentrism and argued against the literal interpretations of the Bible in the non-theological arena, as it contains passages that explicitly contradicted heliocentrism (the most quoted being the one where Joshua commands the Sun and Moon to stand still over Canaan).[[note]]Although a quick bit of thinking shows even this to be reconcilable: Stopping the Moon is no problem (since it actually ''does'' revolve around the Earth, and the Copernican system recognized that), and in a heliocentric system, having the Sun "stand still" over Canaan means "the Earth stops rotating around its axis, making the Sun indeed 'stand still over' Canaan". It was interpretative dances like this one the Church was working on when Galileo began his shouting.[[/note]] Taking to the debate floor, he insisted that the Bible and nature must agree as both proceeded from the same creator, and began insisting Scripture be reinterpreted to suit the theory he couldn't quite prove. Just to make it worse, as Europe was in the midst of the UsefulNotes/ThirtyYearsWar, which pitted basically all the Catholic powers of Continental Europe against basically all the Protestant ones, everyone was a bit touchy about religious doctrine, and Galileo's abrasive personality and previous clashes with Jesuit scientists really weren't helping his cause. In 1616, he appeared before Pope Paul V; the pope, weary of controversy, turned things over to the Holy Office, which condemned the theory. Later, Galileo made a request of a friend - Cardinal Robert Bellarmine, a Jesuit; he was granted a certificate that allowed him not to hold or defend heliocentrism, [[LoopholeAbuse but to conjecture it]]. Later, he met with another pope (and a personal friend), Urban VIII, in 1623. The Pope granted Galileo permission to write on the subject, cautioned him not to advocate it, instead presenting the arguments for or against it. [[RunningGag Not happening]]. What Galileo actually wrote (in the form of a dialogue), while technically presenting the arguments for both sides, was clearly in favor of heliocentrism, and the arguments against it -- including the ones offered by his friend the Pope -- were placed in the mouth of the character named "Simplicio" (i.e. "Simpleton"), who was a debater of obviously inferior intelligence and status than the one arguing heliocentrism. Galileo however claimed Simplicio was actually named after [[http://en.wikipedia.org/wiki/Simplicius_of_Cilicia Simplicius of Cilicia]], a sixth-century commentator on Aristotle, but it's not entirely clear if this is true or he was simply trying to backpedal; given his personality, both are about equally possible.
** The Vatican assigned two Jesuits, Christoph Scheiner and Orazio Grassi, to look into Galileo's science. Both had solid credentials as astronomers. However, Galileo had managed to alienate both of them. Schiener was one of the first astronomers to observe sunspots and was, as far as he knew, the first to describe them in a scientific paper (in fact, the first paper on sunspots was published the previous year by David Fabricius, but his paper was unknown outside of Germany.) Galileo attempted to grab the glory of having first seen sunspots from Scheiner, and compounded this by plagiarizing Scheiner in his own paper. Grassi and Galileo, for their part, disagreed on the nature of comets. What made things interesting was that Grassi was right and Galileo was wrong. Grassi had observed a comet over a period of time, and had noticed that the moon moved faster in the sky than the comet did; Grassi correctly assumed that the comet was further from the Earth than the moon was. Galileo believed that they were optical illusions in the atmosphere. Galileo wrote an essay, ''Il Saggiatore'' -- "The Assayer" -- attacking Grassi and his theory. This essay is still taught in Italian schools as a masterpiece of polemical writing. Naturally, having been held up to ridicule, Grassi was no friend to Galileo.

* Positive Christianity was a movement in Nazi Germany that attempted to reform Christianity by incorporating Nazi ideology. Explicitly not dependent on either the Apostle's Creed or the faith in Christ as the Son of God, Positive Christianity attempted to emphasize the "active" rather than "passive" aspects of Jesus' life and recharacterized him as a combative activist who fought the institutions of his day. Like Marcionism, Positive Christianity considered the Old Testament non-canon and associated it with Judaism; unlike Marcionism, this rejection was motivated by racially-based hatred of the Jews as a people. Aryanhood was claimed for Jesus, and one of its main planks was the elevation of Aryans, especially Nordics. Positive Christianity was created more for political reasons than religious ones; many leading Nazis were hostile towards Christianity, some believing it had been perverted and others rejecting it altogether. However, due to the political significance of Christianity in Germany, moves against its churches had to be made in stages. While attempts were made to unify German Protestantism into a Nazified German Evangelical Church, they met with widespread opposition and most German Protestants didn't side with those promoting Positive Christianity. After the Nazi regime fell in 1945, Positive Christianity faded into obscurity, though some Christian Identity groups espouse its tenets.

* Karaism is a sect of Judaism that rejects the [[Literature/TheTalmud Oral Law]], and accepts only the [[Literature/TheBible Written Law]], a major difference between it and Orthodox Judaism. Once a fairly widespread movement, it has dwindled but there are still a handful around today, mostly in Israel.

*** Someone who was baptized a Catholic (or, possibly, Orthodox), but has now abandoned Christianity completely is an ''apostate''. This includes Catholics who convert to non-Christian religions (e.g. [[Creator/KareemAbdulJabbar Kareem Abdul-Jabbar's]] conversion from Catholicism to Islam) and people who "convert" to atheism (e.g...well...half the famous "Catholics" in America and Europe, really). From the Catholic perspective, it also includes Catholics who convert to Christian sects the Church believes aren't really Christian because they diverge so fundamentally from its understanding of the Christian faith (e.g. William Laurence Sullivan's[[note]]The author of the last book to be banned by the Church[[/note]] conversion to Unitarianism[[note]]At the time still a non-trinitarian Christian sect[[/note]]). (A Catholic who converts to Mormonism--whose Christology and soteriology are singularly bizarre and thus whose position within the Christian tradition is unclear--might be an apostate under this definition.)

* An early, [[Literature/TheBible biblical example]]: "But some men came down from Judea and were teaching the brethren, ‘Unless you are circumcised according to the custom of Moses, you cannot be saved.’" -Acts 15:1. This counts as heresy, in spite of its earliness, since it was previously established that God's grace could be applied to all regardless of circumcision. "And the faithful of the circumcision, who came with Peter, were astonished, for that the grace of the Holy Ghost was poured out upon the Gentiles also." -Acts 10:45 (Acts 10 is good for general context). Paul also has to deal with the Circumcisers in his Letters to the Romans and the Galatians.
* [[UsefulNotes/{{Gnosticism}} Gnostic]] interpretations of Jesus' teachings were declared heretical (in fact, the very ''word'' "heresy" was popularized in the Christian world by Catholic theologian Irenaeus with his anti-Gnostic tracts), and Gnosticism in general also counts for:
** Its antipathy for the material universe, which contradicts God's satisfaction with his work as explicit in the first Creation story of Genesis and the traditional Jesus teachings.
** Instead of human beings being ontologically good creatures in and of themselves, they are spiritual creatures trapped in material form by the Demiurge.[[note]][[Franchise/StarWars Luminous beings are we! Not this crude matter!]][[/note]]
*** Said antipathy for matter likewise denies the Incarnation, which denies Jesus the status of being both True God and True Man.
** The evil, less-than-perfect Demiurge is also claimed to be the true nature of the monotheistic deity worshipped by Jews, Christians, and Muslims, who falsely claims [[{{God}} lordship over all existence]] and [[GodIsEvil manipulates humanity into violence and misery]] [[ForTheEvulz for shits and giggles]]. [[ImAHumanitarian And food]]. This contradicts the orthodox view of God's omnibenevolence and omnipotence.

* [[UsefulNotes/TheCathars Catharism]]'s vogue was in the late 12th and early 13th century. Technically a mixture of Gnostic currents reworked with mostly Christian terminology, there were a few joining principles that connected the various sects under the name. ''Very'' similar to Gnosticism above, the Cathars held a fierce antipathy for the material universe, which they held was created by an [[GodOfEvil evil deity]] (hence, matter is evil), but there exists a [[GodOfGood Good Deity]] who should be worshipped instead (there's a resemblance to UsefulNotes/{{Zoroastrianism}} here). One of the largest Cathar sects was the Albigensians, who wielded a great deal of power in southern France during the 13th century, before being obliterated by the French crown and various crusaders in the Albigensian Crusade. They held that the spirit was created by the good God, but imprisoned by the evil one in a physical body. Hence, the bearing of children - the imprisoning of another human soul in a body - was one of the greatest possible evils; logically, marriage and vaginal sex were forbidden, but anal sex might be technically permissible. Since Catharism was believed to have arisen in Bulgaria (among other things, it was connected to another Gnostic sect, the Bogomils), they were also called ''bougres'' ("Bulgars") in French, from which we get "bugger" and "buggery" for "anal sex" or someone who practices it. They weren't all about the buggery though; there were plenty of fasts that bordered on wilful starvation and lots of severe mortification was practised. Leaders went about in voluntary poverty. Some sects also seemed to believe in ritual suicide, fasting to death after they had been purified.

* Americanism -- A lesser-known heresy, largely due to how oddly specific it is, condemned by Pope Leo XIII in a papal encyclical and a letter to Archbishop of Baltimore, the ''de facto'' leader of the Church in America. Sometimes called a "phantom heresy", due to heated debate about whether or not it genuinely exists, Americanism was the perception, largely by European clergy, that the church in America was overly individualistic in its approach to religious matters. Put more bluntly, it was the idea that American Catholics were free to decide for themselves which Church doctrines they believed, due to the American culture of religious liberty. Leo XIII was particularly concerned about the American tendency to blithely ignore the Church's social teachings -- particularly concerning divorce and economics -- and the American attitude towards the vowed priesthood and other religious institutions, which skewed towards the Protestant side of things. The leaders of the American church were, as you might expect, not terribly flattered by this characterization and denied that it had merit. In response, they asserted that, much like monophysitism above, this one was a proxy for a cultural conflict within the church, namely French and German conservatives projecting their anxieties about growing theological liberalism in Europe onto the church in America (whose hierarchy was diverse, but [[IrishPriest more Irish than anything else]][[note]]Note that because of the historic suppression of the Irish Church by the Protestant English and then British authorities, and the gigantic Irish emigration in the 19th century, the existence of large numbers of Irish priests--let alone Irish prelates--in the United States was something not seen in over 300 years.[[/note]]). Leo XIII himself vacillated on the issue, due in part to being at least somewhat sympathetic to both sides.

** Sufism. A rather loose term for mystical sects than put more emphasis upon the spiritual experience and, usually, are less strict on religious laws--some Sufi ''tariqas'' (literally "ways", usually translated as "orders" or "sects") even use alcohol or other psychoactive drugs (particularly cannabis) in their rituals, even though orthodox Islam regards these as ''makruh'' (discouraged) if not outright ''haraam'' (forbidden). It might have been influenced by Hindu mysticism, which shows in their meditative practices, worship rituals and panentheist-sounding theology. Sufi imams have considerably greater influence on their followers than the mainstream imams. Their departure from what mainstream Muslims consider within bounds varies, and reactions from mainstream Muslims vary between "that is actually kind of legitimate, even if I don't exactly agree" to "let those eccentrics be, as long as they don't cause trouble" to "those are pseudo-Islam, exterminate them." The first attitude is most common among poorer, less educated Muslims, since Sufism is similar to the folk Islam they practice (loaded with saints and shrines and so on), while higher-class/more educated Muslims tend to gravitate toward the second interpretation (essentially regarding Sufism as a somewhat overblown but still basically orthodox and more or less harmless version of folk Islam), and the ultra-purist Wahhabis love knocking down Sufi sites whenever they get a chance.
** Sunni and Shi'a Muslims don't generally regard each other as heretics. The difference was mostly a political one rather than a theological one. Comparison can be drawn between Catholicism and the Eastern Orthodox Church, more or less.
* And finally, all three of the Abrahamic religions "tolerate" (or not) each other to various degrees, the only thing they can agree on being their mutual distaste of polytheism.[[note]]And even that is not consistent. Some Christians, like the Portuguese in India, didn't mind trading with Hindus, at a time when said Hindus were largely ruled over by Muslims who rarely made any serious attempts at converting them. And there was a time where Jews didn't mind the existence of other gods so long as theirs was regarded as the top dog and the focus of worship[[/note]]

** Sufism. A rather loose term for mystical sects than put more emphasis upon the spiritual experience and, usually, are less strict on religious laws--some Sufi ''tariqas'' (literally "ways", usually translated as "orders" or "sects") even use alcohol or other psychoactive drugs (particularly cannabis) in their rituals. It might have been influenced by Hindu mysticism, which shows in their meditative practices, worship rituals and panentheist-sounding theology. Sufi imams have considerably greater influence on their followers than the mainstream imams. Their departure from what mainstream Muslims consider within bounds varies, and reactions from mainstream Muslims vary between "that is actually kind of legitimate, even if I don't exactly agree" to "let those eccentrics be, as long as they don't cause trouble" to "those are pseudo-Islam, exterminate them." The first attitude is most common among poorer, less educated Muslims, since Sufism is similar to the folk Islam they practice (loaded with saints and shrines and so on), while higher-class/more educated Muslims tend to gravitate toward the second interpretation (essentially regarding Sufism as a somewhat overblown but still basically orthodox and more or less harmless version of folk Islam), and the ultra-purist Wahhabis love knocking down Sufi sites whenever they get a chance.

** Sufism. A rather loose term for mystical sects than put more emphasis upon the spiritual experience and, usually, are less strict on religious laws. It might have been influenced by Hindu mysticism, which shows in their meditative practices, worship rituals and panentheist-sounding theology. Sufi imams have considerably greater influence on their followers than the mainstream imams. Their departure from what mainstream Muslims consider within bounds varies, and reactions from mainstream Muslims vary between "that is actually kind of legitimate, even if I don't exactly agree" to "let those eccentrics be, as long as they don't cause trouble" to "those are pseudo-Islam, exterminate them." The first attitude is most common among poorer, less educated Muslims, since Sufism is similar to the folk Islam they practice (loaded with saints and shrines and so on), while higher-class/more educated Muslims tend to gravitate toward the second interpretation (essentially regarding Sufism as a somewhat overblown but still basically orthodox and more or less harmless version of folk Islam), and the ultra-purist Wahhabis love knocking down Sufi sites whenever they get a chance.

* Americanism -- A lesser-known heresy, largely due to how oddly specific it is, condemned by Pope Leo XIII in a papal encyclical and a letter to Archbishop of Baltimore, the ''de facto'' leader of the Church in America. Sometimes called a "phantom heresy", due to heated debate about whether or not it genuinely exists, Americanism was the perception, largely by European clergy, that the church in America was overly individualistic in its approach to religious matters. Put more bluntly, it was the idea that American Catholics were free to decide for themselves which Church doctrines they believed, due to the American culture of religious liberty. Leo XIII was particularly concerned about the American tendency to blithely ignore the Church's social teachings -- particularly concerning divorce and economics -- and the American attitude towards the vowed priesthood and other religious institutions, which skewed towards the Protestant side of things. The leaders of the American church were, as you might expect, not terribly flattered by this characterization and denied that it had merit. In response, they asserted that, much like monophysitism above, this one was a proxy for a cultural conflict within the church, namely French and German conservatives projecting their anxieties about growing theological liberalism in Europe onto the church in America (whose hierarchy was diverse, but [[IrishPriest more Irish than anything else]][[note]]Note that because of the historic suppression of the Irish Church by the Protestant British authorities, and the gigantic Irish emigration in the 19th century, the existence of large numbers of Irish priests--let alone Irish prelates--in the United States was something not seen in over 300 years.[[/note]]). Leo XIII himself vacillated on the issue, due in part to being at least somewhat sympathetic to both sides.

* Jansenism -- 17th century. Cornelius Jansen, the bishop of Ypres in what was then French-controlled Flanders (it is today in Belgium), wrote a paper on Augustine that redefined the doctrine of grace. The Jansenists were a rigorist sect that taught, basically, an adaptation of the Calvinist Protestant soteriology to Catholicism. (Considering that Jansen was originally from the Netherlands, where Calvinist Reformed Protestantism was strong, this is hardly surprising). In this book, Jansen states that man's free will is incapable of any moral goodness. All man's actions proceed either from earthly desires, which stem from concupiscence, or from heavenly desires, which are produced by grace. Each exercises an urgent influence on the human will, which in consequence of its lack of freedom always follows the pressure of the stronger desire. Implicit in Jansenism is the denial of the supernatural order, the possibility of either rejection or acceptance of grace. Accordingly, those who receive the grace will be saved; they are the predestined. All others will be lost. Jansenism was condemned as heretical in five major propositions by Pope Innocent X in 1653. It was re-condemned by Pope Alexander VII in 1656, when Jansenists claimed that their doctrine was misrepresented.

* Feeneyism -- Quite possibly the youngest heresy on this list, and one of the few true American-born heresies, this one erupted sometime around World War II, when Fr. Leonard Feeney, a Jesuit priest, began to preach a very distorted version of the Church tenet ''extra Ecclesiam, nulla salus'', or "No salvation outside the Church." Feeney taught this to mean essentially that everyone who was not a formally baptized Catholic was, without a doubt, going to or already had gone to Hell, considered heretical due both to the Catholic teaching that it is impossible to know with certainty who is in Hell (or to declare on such matters dogmatically)[[note]]The "declare dogmatically" bit is important; a Catholic isn't breaking any rules by saying certain people are only ''probably'' in Hell, or that they believe that a person is in Hell without knowing for sure, or even saying that a person is in Hell if they were doing so--for example--only as [[Literature/TheDivineComedy part of an obvious literary device in a poem expounding on Christian principles of personal spiritual growth]] and ''totally'' not seriously suggesting that those people are actually in Hell. Right, [[Creator/DanteAlighieri Dante]]? You weren't ''seriously'' saying there are Popes in Hell, ''right''?[[/note]] and a denial of several Catholic teachings on the salvation of non-Catholics. Feeney was a notorious and vocal anti-Semite, so the implications of this doctrine, i.e. that Jews were categorically damned, was neither lost on him nor unintentional. The fact that he was also open to declaring anyone who differed with him even slightly a heretic, [[RefugeInAudacity up to and including a previous Pope, Pius IX,]] didn't exactly endear him to the church, and his interpretation of ''nulla salus'' was NOT from any magisterial authority, but from his private interpretation of Scripture.[[note]]Namely, he interpreted Mark 16 more strictly than was considered acceptable by the Church. Feeney's explanation was that the "true" doctrine had been gradually undermined by renegade clergy.[[/note]] In the end, Feeney was ordered by Pope Pius XII to knock it off and come to Rome to explain himself, and when he refused, he was dismissed from the Jesuits in 1949 and ultimately excommunicated in 1953, an excommunication only lifted as recently as 1972.[[note]]The fact that the excommunication was lifted without a recantation is sometimes used by Feeney's fans as a justification for supporting this view. Needless to say, that's not how excommunication works, and Feeneyism has been consistently condemned by the Church since then. Ironically, the rescinding of the excommunication was probably motivated by a desire not to have an aging priest be denied the final sacraments just for being a stubborn ass, meaning Feeney was a recipient of the mercy he militantly attempted to deny to others.[[/note]]

The issue was that proponents of heliocentrism were unable to counter the strongest argument against it, which had been proposed by ''Aristotle himself''--if heliocentrism were true, there should be observable parallax shifts in the position of the stars as the Earth moved. Now, there ''are'' observable parallax shifts, but the technology to demonstrate that hadn't been developed until the eighteenth century--decades ''after Galileo's death''.[[note]]The distance between the stars is several light-years, very large in comparison to Earth's orbit, with a diameter of about 16.6 light-'''minutes'''[[/note]]. Until that point, the evidence suggested that the stars' positions were fixed relative to the Earth, and thus, only the Sun, Moon, and other planets were moving. Copernicus' (correct) explanation that the stars were too far away to exhibit visible parallax was not accepted, even by non-geocentrists like Tycho Brahe. Scientists back then, more used to the smaller-sized universe proposed by Aristotle and Plato, fundamentally had trouble wrapping their heads around the great size and vast distances between celestial objects needed to accommodate a heliocentric universe[[note]]Which themselves are minuscule compared to the gargantuan size and mind-numbingly vast distances of the actual universe described by modern astronomy and cosmology, but let's not get ahead of ourselves[[/note]] and proposed a "geoheliocentric" system in which the Sun, Moon, and stars revolved around a stationary Earth, while almost everything else either revolved around the Sun or revolved around something that revolved around the Sun. This system "worked" inasmuch as it didn't contradict the observed evidence (until the parallax shifts were observed), but was criticized for being more complicated and less elegant than pure heliocentrism. Galileo adopted this critique, but tried to remain restrained in his opinions in the letter to the duchess. However, being a bullheaded and rather stubborn sort of fellow, Galileo later doubled down on heliocentrism, and ''that'' got him in trouble.

*** Someone who was never validly baptized (again according to Catholic rules) and never believed in what the Church considers true Christian doctrine is ''incredulous''. Thus most people born non-Christian or born Protestants (as they have strong disagreements on issues of doctrine and from the Catholic perspective are not considered to have had valid baptisms) are "incredulous" from the Church's point of view.

* The original Nazarene sect was considered a heresy in Judaism. Only once they started recruiting non-Jews without putting them through the proper conversion rituals did Christianity become a distinct religion, whose differences initially amounted to that before deepening over time. Modern Messianic Judaism, or groups who claim to be Jews who believe Jesus is the messiah, is still considered a heresy and more or less a form of Christianity dressed up as Judaism. What sealed the break was the expelling of the Christians from the synagogues in AD 82. Up until this point, relations were tense, but it was still a common practice for an Israelite Christian to go to the synagogue on Sabbath morning, and then go home, rest up, and attend Mass in the evening. After the expulsion, Christians no longer regarded themselves as a sect of Judaism, even if they were born Jewish.

* And finally, all three of the Abrahamic religions "tolerate" (or not) each other to various degrees, they only thing they can agree on being their mutual distaste of polytheism.[[note]]And even that is not consistent. Some Christians, like the Portuguese in India, didn't mind trading with Hindus, at a time when said Hindus were largely ruled over by Muslims who rarely made any serious attempts at converting them. And there was a time where Jews didn't mind the existence of other gods so long as theirs was regarded as the top dog and the focus of worship[[/note]]

* And finally, all three of the Abrahamic religions "tolerate" (or not) each other to various degrees, they only thing they can agree on being their mutual distaste of polytheism.[[note]]And even that is not consistent. Some Christians, like the Portuguese in India, didn't mind to trade with Hindus, and there was a time where Jews didn't mind the existence of other gods so long as theirs was regarded as the top dog and the focus of worship[[/note]]

* The original Nazarene sect was considered a heresy in Judaism. Only once they started recruiting non-Jews without putting them through the proper conversion, Christianity became a distinct religion, whose differences initially amounted to that before deepening over time. (Modern Messianic Judaism, or groups who claim to be Jews who believe Jesus is the messiah, is still considered a heresy and more or less a form of Christianity dressed up as Judaism.) What sealed the break was the expelling of the Christians from the synagogues in AD 82. Up until this point, relations were tense, but it was still a common practice for an Israelite Christian to go to the synagogue on Sabbath morning, and then go home, rest up, and attend Mass in the evening. After the expulsion, Christians no longer regarded themselves as a sect of Judaism, even if they were born Jews.

* Orthodox Judaism, which was codified by the rabbis who wrote Literature/TheTalmud after the Second Temple in Jerusalem was destroyed by the Romans and the Jews were forced into exile, sees itself as the true Jewish religion in an unbroken tradition going back to Moses himself. (Other Jewish sects that existed around that time, like the Essenes and Zealots, have long since died out.) For most of the last two millennia it more or less was the only form of Judaism, other than the Karaites, and is still the sect with the most members. In the last couple of centuries other Jewish denominations have come into being like Conservative Judaism (which is traditionalist like Orthodox Judaism, but not as strict), Reform Judaism (which is progressive and not strict about Jewish law) and Reconstruction Judaism (which sees Judaism as less of a religion and more of a culture). Orthodox Judaism sees all of these as heresies, and conversions to them are not accepted by Orthodox rabbis, but they may still be seen as ''ethnic'' Jews who can return to Judaism at any time if they undergo a proper conversion. Orthodox and Conservative Jews tend to agree on more and get along better than Orthodox Jews do with Reform or Reconstruction Jews, who tend to agree more with each other.

As a point of clarity, while Protestantism is in fact considered a heresy, most ''Protestants'' are not considered heretics anymore. Since, unlike the original generation, they were never Catholic in the first place, and because Protestant baptisms are not generally recognized as valid by the Catholic Church, being a Catholic heretic is rather impossible. A convert from Catholicism to Protestantism might be considered a heretic if the particular Protestant sect largely agrees on doctrine but differs on a few key points (e.g. if someone converts from Catholicism to High Church Lutheranism, which is mostly like Catholicism but still holds to the same ideas that made Luther a heretic). Additionally, the position is somewhat complicated by Anglicanism, especially as practised by the Church of England, which was originally intended as - basically - Catholicism where the Church reported to the King, UsefulNotes/HenryVIII, rather than the Pope (which, ironically, was not terribly different from how the Catholic Spain worked, only simply more overt and extreme).[[note]]Although Spain later came to be known as the workhorse of the Counter-Reformation, their church and, yes, the UsefulNotes/SpanishInquisition, reported first to the king and then to the Pope (and the latter was sometimes eschewed on the presumption the king would later report to the Pope himself). In other words, while not rejecting the Pope's authority, in Spain the church was subservient to the state and not vice versa as in many other Catholic lands of the time. This came to its biggest stretch when UsefulNotes/CharlesV bullied Pope Clement VII into kowtowing to him by literal military force, all while claiming and genuinely considering himself to be ''the'' Catholic Monarch. Clement was left so upset that his attempts to overcompensate it eventually caused the Henry VIII affair.[[/note]] Even today, the High Church part of the C of E bears a great deal of resemblance to Catholicism. The transition to a fully Protestant church under subsequent monarchs, and the according changes in doctrine, ritual, and teaching, have derailed attempts at reproachment. The official position of the Church is that it is "both Catholic and Reformed", i.e. a Protestant church that looks and behaves Catholic. There have been movements within the Church of England to more greatly emphasize its Catholic heritage, but the clerics involved tend to either stop short of fully embracing Catholic doctrine or simply convert to Catholicism. One of those movements was the Oxford Movement, which featured the theologians such as Edward Bouverie Pusey and John Henry Newman. Newman himself would eventually convert to Catholicism, to the shock and outrage of the Church of England.

* A ''very'' famous example was given to the world in the teachings of Arius, who effectively used orthodox language to teach that Jesus was not divine, but a creature made by God. When Constantine legalized Christianity, one of the first things done by the leaders of the Church was to define and formalize what the belief system of Christianity actually held-Arius, who famously was supported by many bishops and excommunicated by others, gave an explanation of his beliefs to the Council of Nicaea in 325 and was solemnly condemned[[note]]Legend has it that a certain [[SantaClaus St. Nicholas]] was [[SecretCharacter also present]] at the council, and became so [[BerserkButton angry at Arius' teaching]] that he ''punched the man out''. St. Nicholas is not included in the official registry of bishops present, but that only conspiracy theories adds to the fun]].[[/note]]; the Council of Nicaea formally proclaimed the divinity of Jesus Christ. Arianism was also an issue at the First Council of Constantinople in 381, where the divinity of the Holy Spirit was also declared.\\

* Feeneyism -- Quite possibly the youngest heresy on this list, and one of the few true American-born heresies, this one erupted sometime around World War Two, when Fr. Leonard Feeney, a Jesuit priest, began to preach a very distorted version of the Church tenet ''extra Ecclesiam, nulla salus'', or "No salvation outside the Church." Feeney taught this to mean essentially that everyone who was not a formally baptized Catholic was, without a doubt, going to or already had gone to Hell, considered heretical due both to the Catholic teaching that it is impossible to know with certainty who is in Hell (or to declare on such matters dogmatically)[[note]]The "declare dogmatically" bit is important; a Catholic isn't breaking any rules by saying certain people are only ''probably'' in Hell, or that they believe that a person is in Hell without knowing for sure, or even saying that a person is in Hell if they were doing so--for example--only as [[Literature/TheDivineComedy part of an obvious literary device in a poem expounding on Christian principles of personal spiritual growth]] and ''totally'' not seriously suggesting that those people are actually in Hell. Right, [[Creator/DanteAlighieri Dante]]? You weren't ''seriously'' saying there are Popes in Hell, ''right''?[[/note]] and a denial of several Catholic teachings on the salvation of non-Catholics. Feeney was a notorious and vocal anti-Semite, so the implications of this doctrine, i.e. that Jews were categorically damned, was neither lost on him nor unintentional. The fact that he was also open to declaring anyone who differed with him even slightly a heretic, [[RefugeInAudacity up to and including a previous Pope, Pius IX,]] didn't exactly endear him to the church, and his interpretation of ''nulla salus'' was NOT from any magisterial authority, but from his private interpretation of Scripture.[[note]]Namely, he interpreted Mark 16 more strictly than was considered acceptable by the Church. Feeney's explanation was that the "true" doctrine had been gradually undermined by renegade clergy.[[/note]] In the end, Feeney was ordered by Pope Pius XII to knock it off and come to Rome to explain himself, and when he refused, he was dismissed from the Jesuits in 1949 and ultimately excommunicated in 1953, an excommunication only lifted as recently as 1972.[[note]]The fact that the excommunication was lifted without a recantation is sometimes used by Feeney's fans as a justification for supporting this view. Needless to say, that's not how excommunication works, and Feeneyism has been consistently condemned by the Church since then. Ironically, the rescinding of the excommunication was probably motivated by a desire not to have an aging priest be denied the final sacraments just for being a stubborn ass, meaning Feeney was a recipient of the mercy he militantly attempted to deny to others.[[/note]]

* And finally, all three of the Abrahamic religions "tolerate" (or not) each other to various degrees, they only thing they can agree on being their mutual distaste of polytheism.[[note]]And even that is not consistent. Some Christians, like the Portuguese in India, didn't mind to trade with Hindus, and there was a time where Jews didn't mind the existence of other gods so long as theirs is regarded as the top dog and the focus of worship[[/note]]

Iconoclasm, as a political issue in the Byzantine Empire, lasted from around 726 to 843, with a hiatus from 787 to 814, and wound up - essentially - as a wrangle between Church and State over Imperial power over the Church (the Church won).[[note]]To give an idea of the ongoing effect: Centuries later, another emperor, Alexios I Komnenos, seized icons for their gold in the face of the simultaneous advance of the Turks from the east and Robert Guiscard's Normans from the west. The Church raised the specter of iconoclasm to drum up opposition to this move and seemed likely to raise an uproar. However, they didn't count on Alexios cleverly deflecting these accusations by being crassly materialistic about his grab: he said he had no problem with icons, it was just that the Emperor was empowered to [[IDidWhatIHadToDo do whatever was necessary--including seize holy images and other Church property--to save Christendom]]. He also distracted the Church establishment by accusing a prominent philosopher of heresy. Whether or not the icon seizure worked, it certainly didn't doom the nation; Alexios' reign marked the beginning of the last expansion of the Empire.[[/note]] Iconoclasm briefly reappeared in the initial stages of UsefulNotes/TheProtestantReformation mostly as a push back against the perceived decadence of the Catholics, but largely disappeared over the years, the only noticeable remnant being most Protestants' tendency to wear a bare cross instead of a Crucifix and building fairly austere and unadorned churches (until the High Church Anglicans decided to up the "High Church" part with the Oxford Movement, though they still don’t do crucifixes as much as Catholics).[[note]]This sets aside the somewhat complicated High Church Lutheranism that formed the state religion in the post-Reformation Nordic Countries. It's really not worth getting into unless you have a particular fascination with Danish or Swedish history.[[/note]]

Popular history associates this with Byzantine Emperor Leo III "The Isaurian", who had lived near the border with Muslim-ruled Syria, but although this has a grain of truth to it (Leo genuinely was not a big fan of icons), iconoclasm as imperial--and therefore Eastern Orthodox--policy was rather exaggerated by the generation that killed it (with the assistance of the Pope in Rome--at that time, again, the Church in Rome had not yet formally split from the Church in Constantinople, so this fight was basically one within Catholicism--albeit a Catholicism with a focus on the East and one where the Pope was increasingly looking to escape from the Byzantine Emperor's shadow). A good bit of the issue was that icons tended to be richly decorated with gold, silver, and jewels; if the images were destroyed, the State could seize the precious materials, converting the metal into coins and selling the jewels for cash.[[note]]At about the same time, Emperor Wuzong of [[UsefulNotes/DynastiesFromShangToQing Tang]] was doing something similar with the country's great Buddhist bronzes, as well as other Buddhist statutes in gold and silver, as part of his great persecution of Buddhists and other "foreign" faiths. The Chinese state faced less pushback than the Roman, and a truly impressive number of statues were melted down and minted into coin. There's no suggestion that these events had any direct connection, but it's striking that two desperate empires came to similar conclusions in the 9th century. Ironically, it was the Romans that survived, while the Tang had all but collapsed within 60 years of Wuzong's reign. (This isn't to say that the statute-melting doomed them--the liquidity probably helped buy the Tang some of those 60 years, and there's no suggestion that the persecution of Buddhism was a significant factor in the loss of stability--but it is striking.)[[/note]] At the very least, iconoclasts argued, icons were a horrible waste of resources in the face of continuing Arab raids and repeated Arab attempts on Constantinople itself.\\

The endurance of the ancient division is largely a function of politics: the conflict between the Monophysites and the "Orthodox" (that is, the ones adopting the present Catholic--and Eastern Orthodox--Christology) was a hot religious and political issue during the early years of UsefulNotes/TheByzantineEmpire, with Monophysitism being dominant in the empire's eastern provinces (Egypt and Syria, mostly, though it was also adopted by the churches of Armenia[[note]]Which was no longer an independent state (the independent Armenian kingdom had been gone for over twenty years by the time of the Council of Chalcedon in 451) and the Armenian lands had been divided between the Roman and Sasanian Persian Empires. The Armenian Church was, therefore, the only all-Armenia institution remaining, and as a Christian organization, the ([[UsefulNotes/{{Zoroastrianism}} Zoroastrian]]) Persians were always suspicious that the Church was a cat's paw for Constantinople. The theological difference with the officially sanctioned Roman state church helped the Armenian Church show it wasn't aligned with Constantinople and so could operate without too much interference. For its part, Ctesiphon did what it could to encourage Monophysitism in the hopes that the Christological dispute would lead the Armenian Church to look to Persia for support against Chalcedonian Orthodoxy. (The Sasanian Persians were used to this kind of dancing, having propped up the Nestorian Church of the East in Mesopotamia for basically the same reason. They were actually fairly effective at deploying various religions as tools of power projection more generally, supporting Jewish communities across the Middle East and UsefulNotes/{{Manichaeism}} in Central Asia, both to great effect (at one point, they even got Yemen to convert to Judaism as a move to align with Persia). About the only religion they ''didn't'' push was their own orthodox Zoroastrianism.) These efforts proved fruitless in Armenia; it turned out that despite the success of Monophysitism in Armenia, the Armenian Church and the Armenians more generally really were more inclined to favor the Romans over the Persians in secular affairs when they could help it.[[/note]] and Ethiopia[[note]]Which was was not a province but a valued ally of Byzantium against Persian interests in Yemen and the Arabian Peninsula more broadly. Ethiopia attacked Yemen about 130 years after the conversion to Judaism basically to add another front to the wider war between the Romans and Persians. (They would hold onto Yemen until the rise of Islam a generation or two later made the whole Roman-Persian contention irrelevant.) The Ethiopian church was administered through the Monophysite Patriarchate of Alexandria in Egypt; this suited the Ethiopian monarchy and church just fine, as it insulated the Ethiopian Church from Constantinople's (and thus the Emperor's) influence.[[/note]]) and Orthodoxy being dominant in the west (in the Greek-speaking heartland of Anatolia and the Balkans/Greece). While the theological differences were genuine and often sincerely held, a lot of the actual heat was more reflective of the non-Greek-speaking East's desire to remain distinct in a Greek-dominated empire, as well as factional power politics; different Emperors backed Chalcedonian or Monophysite clerics at different times for political reasons.\\

* A ''very'' famous example was given to the world in the teachings of Arius, who effectively used orthodox language to teach that Jesus was not divine, but a creature made by God. When Constantine legalized Christianity, one of the first things done by the leaders of the Church was to define and formalize what the belief system of Christianity actually held-Arius, who famously was supported by many bishops and excommunicated by others, gave an explanation of his beliefs to the Council of Nicaea in 325 and was solemnly condemned[[note]]Legend has it that a certain [[SantaClaus St. Nicholas]] was [[SecretCharacter also present]] at the council, and became so [[BerserkButton angry at Arius' teaching]] that he ''punched the man out''. St. Nicholas is not included in the official registry of bishops present, but that only [[UsefulNotes/ConspiracyTheories adds to the fun]].[[/note]]; the Council of Nicaea formally proclaimed the divinity of Jesus Christ. Arianism was also an issue at the First Council of Constantinople in 381, where the divinity of the Holy Spirit was also declared.\\

* Iconoclasm ("icon smashing") first showed up in the 7th and 8th centuries. The essence of the claim was that it was sinful to make pictures or statues of Christ and the saints, based on the Second Commandment ("Thou shalt not make unto thee any graven image..."). The Catholic (and Orthodox) view is that God had [[Literature/TheBible commanded]] the creation of religious statues (Ex. 25:18–20; 1 Chr. 28:18–19), including symbolic representations of Christ (cf. Num. 21:8–9 w/ John 3:14). It was originally inspired by the Muslim blanket ban on representations of God and the Prophets (which often ended up as a blanket ban on representational art, just to be safe) and the Old Testament's emphasis against idolatry. Iconoclasts claimed that the Muslim eschewal of images was pleasing to God, as evidenced by the Muslims' military success against all enemies, or at the very least that Christian attachment to images had gotten out of hand and that God had sent the Muslims to punish the Christians for their crypto-idolatry.\\

The endurance of the ancient division is largely a function of politics: the conflict between the Monophysites and the "Orthodox" (that is, the ones adopting the present Catholic--and Eastern Orthodox--Christology) was a hot religious and political issue during the early years of UsefulNotes/TheByzantineEmpire, with Monophysitism being dominant in the empire's eastern provinces (Egypt and Syria, mostly, though it was also adopted by the churches of Armenia[[note]]Which was no longer an independent state (the independent Armenian kingdom had been gone for over twenty years by the time of the Council of Chalcedon in 451) and the Armenian lands had been divided between the Roman and Sasanian Persian Empires. The Armenian Church was, therefore, the only all-Armenia institution remaining, and as a Christian organization, the (Zoroastrian) Persians were always suspicious that the Church was a cat's paw for Constantinople. The theological difference with the officially sanctioned Roman state church helped the Armenian Church show it wasn't aligned with Constantinople and so could operate without too much interference. For its part, Ctesiphon did what it could to encourage Monophysitism in the hopes that the Christological dispute would lead the Armenian Church to look to Persia for support against Chalcedonian Orthodoxy. (The Sasanian Persians were used to this kind of dancing, having propped up the Nestorian Church of the East in Mesopotamia for basically the same reason. They were actually fairly effective at deploying various religions as tools of power projection more generally, supporting Jewish communities across the Middle East and UsefulNotes/{{Manichaeism}} in Central Asia, both to great effect (at one point, they even got Yemen to convert to Judaism as a move to align with Persia). About the only religion they ''didn't'' push was their own orthodox Zoroastrianism.) These efforts proved fruitless in Armenia; it turned out that despite the success of Monophysitism in Armenia, the Armenian Church and the Armenians more generally really were more inclined to favor the Romans over the Persians in secular affairs when they could help it.[[/note]] and Ethiopia[[note]]Which was was not a province but a valued ally of Byzantium against Persian interests in Yemen and the Arabian Peninsula more broadly. Ethiopia attacked Yemen about 130 years after the conversion to Judaism basically to add another front to the wider war between the Romans and Persians. (They would hold onto Yemen until the rise of Islam a generation or two later made the whole Roman-Persian contention irrelevant.) The Ethiopian church was administered through the Monophysite Patriarchate of Alexandria in Egypt; this suited the Ethiopian monarchy and church just fine, as it insulated the Ethiopian Church from Constantinople's (and thus the Emperor's) influence.[[/note]]) and Orthodoxy being dominant in the west (in the Greek-speaking heartland of Anatolia and the Balkans/Greece). While the theological differences were genuine and often sincerely held, a lot of the actual heat was more reflective of the non-Greek-speaking East's desire to remain distinct in a Greek-dominated empire, as well as factional power politics; different Emperors backed Chalcedonian or Monophysite clerics at different times for political reasons.\\

*** A Catholic is one who believes in Church doctrine and recognizes the authority of the Church hierarchy.
*** Someone who never believed in what the Church considers true Christian doctrine is ''incredulous''. Thus most people born non-Christian or born Protestants (as they have strong disagreements on issues of doctrine and from the Catholic perspective are not considered to have had valid baptisms) are "incredulous" from the Church's point of view.

** You may have noticed something important in that definition--the heresy is only a heresy when it knowingly and willfully contradicts established Catholic teaching, and a person is only a heretic if he/she holds a heretical belief and has had valid (i.e. Catholic[[note]]Or Orthodox, probably[[/note]]) baptism. The Catholic Church has a habit of not granting strict definitions to doctrine until it becomes a major issue, due to issues of opportunity and urgency--the divinity of Christ, while held and intuited by a large portion of Christians to varying degrees, wasn't formally defined until after Constantine legalized Christianity in the early 4th century, for example.

*** Someone who was baptized a Catholic (or, possibly, Orthodox), but has now abandoned Christianity completely is an ''apostate''. This includes Catholics who convert to non-Christian religions (e.g. [[Creator/KareemAbdulJabbar Kareem Abdul-Jabbar's]] conversion from Catholicism to Islam) and people who "convert" to atheism (e.g...well...half the famous "Catholics" in America, really). From the Catholic perspective, it also includes Catholics who convert to Christian sects the Church believes aren't really Christian because they diverge so fundamentally from its understanding of the Christian faith (e.g. William Laurence Sullivan's[[note]]The author of the last book to be banned by the Church[[/note]] conversion to Unitarianism[[note]]At the time still a non-trinitarian Christian sect[[/note]]). (A Catholic who converts to Mormonism--whose Christology and soteriology are singularly bizarre and thus whose position within the Christian tradition is unclear--might be an apostate under this definition.)

** Its antipathy for the material universe, which contradicts God's satisfaction with his work as explicit in the first Creation story of Genesis.

** The Demiurge is also claimed to be the true nature of the monotheistic deity worshipped by Jews, Christians, and Muslims, who falsely claims [[{{God}} lordship over all existence]] and [[GodIsEvil manipulates humanity into violence and misery]] [[ForTheEvulz for shits and giggles]]. [[ImAHumanitarian And food]]. This contradicts the orthodox view of God's omnibenevolence.
* Marcionism, which may or may not be a form of Gnosticism depending on what definition is used, was a dualist belief that claimed that the wrathful [[GodIsEvil Old Testament God]] is an inferior being to the loving [[GodIsGood New Testament God]]. Developed by Marcion of Sinope, who accordingly rejected all of the Old Testament and most of the New, keeping only the Gospel of Luke (heavily modified by him into the Gospel of Marcion) and St. Paul's letters. Having died in the early 2nd Century, Marcion is one of the very first declared heretics in the Church.

** Origen, a Christian mystic, was accused of Heresy because some of his ideas were viewed as "too platonic" [[http://www.ccel.org/ccel/schaff/npnf214.xii.ix.html for various reasons.]] Despite popular belief, [[http://en.wikipedia.org/wiki/Universal_reconciliation Universal Redemption]] was not one of the said reasons.
* Adoptionism, like Sabellianism, preached that God is a singular entity rather than being divided into three. It denies the pre-existence of Christ and claims that he only became divine after being "adopted" as the Son of God at some point (the most common options are his baptism, his resurrection and his ascension). Moreover, it insists that while Jesus has remained divine since his adoption, he is not equal to God the Father. This idea is essentially the opposite of the now-orthodox doctrine that the Son was a divine being who became human, did the Father's will on Earth, and then returned to heaven. While it was once believed that this "adoptionist" or "low" Christology predated the "incarnationist" or "high" Christology and was the mainstream view until the notion of a pre-existing divine Jesus was developed and eventually supplanted the idea that he was merely exalted (adopted as God's son), the current scholarly consensus since the 1970s is that high Christology was developed very early on and coexisted with low Christology. Of course, high Christology eventually won out, and Adoptionism became a heresy. Adoptionism can still be found today, mainly among various strands of Unitarianism and Mormonism.

The endurance of the ancient division is largely a function of politics: the conflict between the Monophysites and the "Orthodox" (that is, the ones adopting the present Catholic--and Eastern Orthodox--Christology) was a hot religious and political issue during the early years of UsefulNotes/TheByzantineEmpire, with Monophysitism being dominant in the empire's eastern provinces (Egypt and Syria, mostly, though it was also adopted by the churches of Armenia[[note]]Which was no longer an independent state (the independent Armenian kingdom had been gone for over twenty years by the time of the Council of Chalcedon in 451) and the Armenian lands had been divided between the Roman and Sasanian Persian Empires. The Armenian Church was, therefore, the only all-Armenia institution remaining, and as a Christian organization, the (Zoroastrian) Persians were always suspicious that the Church was a cat's paw for Constantinople. The theological difference with the officially sanctioned Roman state church helped the Armenian Church show it wasn't aligned with Constantinople and so could operate without too much interference. For its part, Ctesiphon did what it could to encourage Monophysitism in the hopes that the Christological dispute would lead the Armenian Church to look to Persia for support against Chalcedonian Orthodoxy. (The Sasanian Persians were used to this kind of dancing, having propped up the Nestorian Church of the East in Mesopotamia for basically the same reason. They were actually fairly effective at deploying various religions as tools of power projection more generally, supporting Jewish communities across the Middle East and Manicheanism in Central Asia, both to great effect (at one point, they even got Yemen to convert to Judaism as a move to align with Persia). About the only religion they ''didn't'' push was their own orthodox Zoroastrianism.) These efforts proved fruitless in Armenia; it turned out that despite the success of Monophysitism in Armenia, the Armenian Church and the Armenians more generally really were more inclined to favor the Romans over the Persians in secular affairs when they could help it.[[/note]] and Ethiopia[[note]]Which was was not a province but a valued ally of Byzantium against Persian interests in Yemen and the Arabian Peninsula more broadly. Ethiopia attacked Yemen about 130 years after the conversion to Judaism basically to add another front to the wider war between the Romans and Persians. (They would hold onto Yemen until the rise of Islam a generation or two later made the whole Roman-Persian contention irrelevant.) The Ethiopian church was administered through the Monophysite Patriarchate of Alexandria in Egypt; this suited the Ethiopian monarchy and church just fine, as it insulated the Ethiopian Church from Constantinople's (and thus the Emperor's) influence.[[/note]]) and Orthodoxy being dominant in the west (in the Greek-speaking heartland of Anatolia and the Balkans/Greece). While the theological differences were genuine and often sincerely held, a lot of the actual heat was more reflective of the non-Greek-speaking East's desire to remain distinct in a Greek-dominated empire, as well as factional power politics; different Emperors backed Chalcedonian or Monophysite clerics at different times for political reasons.\\

* [[UsefulNotes/TheCathars Catharism]]'s vogue was in the late 12th and early 13th century. Technically a mixture of non-Christian religions reworked with Christian terminology, there were a few joining principles that connected the various sects under the name. ''Very'' similar to Gnosticism above, the Cathars held a fierce antipathy for the material universe, which they held was created by an [[GodOfEvil evil deity]] (hence, matter is evil), but there exists a [[GodOfGood Good Deity]] who should be worshipped instead (there's a resemblance to UsefulNotes/{{Zoroastrianism}} here). One of the largest Cathar sects was the Albigensians, who wielded a great deal of power in southern France during the 13th century, before being obliterated by the French crown and various crusaders in the Albigensian Crusade. They held that the spirit was created by the good God, but imprisoned by the evil one in a physical body. Hence, the bearing of children - the imprisoning of another human soul in a body - was one of the greatest possible evils; logically, marriage and vaginal sex were forbidden, but anal sex might be technically permissible. Since Catharism was believed to have arisen in Bulgaria (among other things, it was connected to another Gnostic sect, the Bogomils), they were also called ''bougres'' ("Bulgars") in French, from which we get "bugger" and "buggery" for "anal sex" or someone who practices it. They weren't all about the buggery though; there were plenty of fasts that bordered on wilful starvation and lots of severe mortification was practised. Leaders went about in voluntary poverty. Some sects also seemed to believe in ritual suicide, fasting to death after they had been purified.

As a point of clarity, while Protestantism is in fact considered a heresy, most ''Protestants'' are not considered heretics. Since they were never Catholic in the first place, and because Protestant baptisms are not generally recognized as valid by the Catholic Church, being a Catholic heretic is rather impossible. A convert from Catholicism to Protestantism might be considered a heretic if the particular Protestant sect largely agrees on doctrine but differs on a few key points (e.g. if someone converts from Catholicism to High Church Lutheranism, which is mostly like Catholicism but still holds to the same ideas that made Luther a heretic). Additionally, the position is somewhat complicated by Anglicanism, especially as practised by the Church of England, which was originally intended as - basically - Catholicism where the Church reported to the King, Henry VIII, rather than the Pope. Even today, the High Church part of the C of E bears a great deal of resemblance to Catholicism. The transition to a fully Protestant church under subsequent monarchs, and the according changes in doctrine, ritual, and teaching, have derailed attempts at reproachment. The official position of the Church is that it is "both Catholic and Reformed", i.e. a Protestant church that ''looks'' Catholic. There have been movements within the Church of England to more greatly emphasize its Catholic heritage, but the clerics involved tend to either stop short of fully embracing Catholic doctrine or simply convert to Catholicism. One of those movements was the Oxford Movement, which featured the theologians such as Edward Bouverie Pusey and John Henry Newman. Newman himself would eventually convert to Catholicism, to the shock and outrage of the Church of England.

* "Galileo was famously tried before a court for an issue regarding the veracity of heliocentrism" is about as neutral as the pop-cultural understanding of the actual sequence of events is likely to get; most people seem to think Galileo was declared a heretic. Let's start with the context:

** It is commonly assumed that Galileo ''proved'' heliocentrism -- he didn't, exactly. He merely made the biggest noise about it. He started by writing a letter in response to the Grand Duchess of Tuscany saying, in effect, "Well, I wouldn't put ''too'' fine a point on it, but yes, the evidence does ''suggest'' that, scientifically speaking, the Church and Creator/{{Aristotle}} really do have the whole structure of the Universe wrong." Notice all the hedging: Galileo was convinced, but knew he didn't have definitive, incontrovertible proof. His observation that Venus has phases made it ''extremely unlikely'' that geocentrism was true and heliocentrism false, but there were all kinds of other explanations that could have been cooked up to keep the Earth in the middle, even though they were all sort of ridiculous.\\

*** Mind you, Galileo had a critical role in putting a dent in geocentrism. His discovery of UsefulNotes/TheMoonsOfJupiter made the Aristotelian theory that much more difficult to defend--if everything was supposed to go around the Earth, why did these four things go around Jupiter instead? And Galileo and other astronomers of his era kept making similar discoveries, particularly (although not necessarily) after they followed his lead in pointing telescopes at the heavens: if the celestial bodies were supposed to be perfectly spherical, why does the Moon seem to have mountains? Or the Sun seem to have spots? (See below for the bad blood ''that'' raised.) And why, pray tell (as mentioned) did Venus have phases when you looked at it through a telescope? (The math means that if Venus has phases, things have to be pretty wonky up there if everything revolves around the Earth, with the Tychonic geoheliocentrism being the least-wonky.) And perhaps most significantly of all, why did Brahe--working ''without'' a telescope--see a new star (really the supernova [[http://en.wikipedia.org/wiki/SN_1572 SN 1572]]), when both Aristotle and Church doctrine said that the stars were perfect and thus a new star was impossible? And eighty years later, Edmund Halley noted that even the stars were moving--Sirius, Arcturus, and Aldebaran had moved half a degree since the time of the Classical astronomers and their star charts. Finally, about a century after ''that''--at which point everyone with an education accepted heliocentrism already--someone finally measured the parallax of a star, using a device that amounted to a telescope with extra measuring equipment attached. And that was that for geocentrism.

** Unfortunately for Galileo, as we said above, he doubled down on heliocentrism and argued against the literal interpretations of the Bible in the non-theological arena, as it contains passages that explicitly contradicted heliocentrism (the most quoted being the one where Joshua commands the Sun and Moon to stand still over Canaan).[[note]]Although a quick bit of thinking shows even this to be reconcilable: Stopping the Moon is no problem (since it actually ''does'' revolve around the Earth, and the Copernican system recognized that), and in a heliocentric system, having the Sun "stand still" over Canaan means "the Earth stops rotating around its axis, making the Sun indeed 'stand still over' Canaan". It was interpretative dances like this one the Church was working on when Galileo began his shouting.[[/note]] Taking to the debate floor, he insisted that the Bible and nature must agree as both proceeded from the same creator, and began insisting Scripture be reinterpreted to suit the theory he couldn't quite prove. Just to make it worse, as Europe was in the midst of the UsefulNotes/ThirtyYearsWar, which pitted basically all the Catholic powers of Continental Europe against basically all the Protestant ones, everyone was a bit touchy about religious doctrine, and Galileo's abrasive personality and previous clashes with Jesuit scientists really weren't helping his cause. In 1616, he appeared before Pope Paul V; the pope, weary of controversy, turned things over to the Holy Office, which condemned the theory. Later, Galileo made a request of a friend - Cardinal Robert Bellarmine, a Jesuit; he was granted a certificate that allowed him not to hold or defend heliocentrism, [[LoopholeAbuse but to conjecture it]]. Later, he met with another pope (and a personal friend), Urban VIII, in 1623. The Pope granted Galileo permission to write on the subject, cautioned him not to advocate it, instead presenting the arguments for or against it. [[RunningGag Not happening]]. What Galileo actually wrote (in the form of a dialogue), while technically presenting the arguments for both sides, was clearly in favor of heliocentrism, and the arguments against it -- including the ones offered by his friend the pope -- were placed in the mouth of the character named "Simplicio" (i.e. "Simpleton"), who was a debater of obviously inferior intelligence and status than the one arguing heliocentrism. Galileo however claimed Simplicio was actually named after [[http://en.wikipedia.org/wiki/Simplicius_of_Cilicia Simplicius of Cilicia]], a sixth-century commentator on Aristotle. It's not entirely clear if this is true or he was simply trying to backpedal; given his personality, both are about equally possible.
** The Vatican assigned two Jesuits, Christoph Scheiner and Orazio Grassi, to look into Galileo's science. Both had solid credentials as astronomers. However, Galileo had managed to alienate both of them. Schiener was one of the first astronomers to observe sunspots and was, as far as he knew, the first to describe them in a scientific paper (in fact, the first paper on sunspots was published the previous year by David Fabricius, but his paper was unknown outside of Germany.) Galileo attempted to grab the glory of having first seen sunspots from Scheiner, and compounded this by plagiarizing Scheiner in his own paper. Grassi and Galileo disagreed on the nature of comets. What made things interesting was that Grassi was right and Galileo was wrong. Grassi had observed a comet over a period of time, and had noticed that the moon moved faster in the sky than the comet did; Grassi correctly assumed that the comet was further from the Earth than the moon was. Galileo believed that they were optical illusions in the atmosphere. Galileo wrote an essay, ''Il Saggiatore'' -- "The Assayer" -- attacking Grassi and his theory. This essay is still taught in Italian schools as a masterpiece of polemical writing. Naturally, having been held up to ridicule, Grassi was no friend to Galileo.
** Having publicly mocked the Pope, alienating the Jesuits (the Catholic institution ''most'' inclined to accept heliocentrism) to boot with attacks on two of their astronomers, Galileo's actions resulted in the famous trial. In course of the trial, Galileo stayed in fine quarters at the Apostolic Palace while his meals were prepared by the best chef in town. While he eventually recanted his teachings, he was not tortured (he was only threatened); he was actually merely placed under house arrest, at a fine mansion in the countryside belonging to a friend... and given a manservant. Galileo was not explicitly declared a heretic, though he was found to be "''vehemently suspect''" of it; the testimony from his trial (Galileo was tried before an ordinary tribunal) was brought before a group of ten cardinals. Three of them refused to sign his verdict, but his works were eventually condemned.

* Islam has very strict instructions on what its followers should and shouldn't do, and practices that can't be traced back to the Prophet Muhammad himself[[note]]Or at least, that which goes against the spirit of Islam-there was no Internet in his time, but that doesn't make the Internet forbidden[[/note]] are regarded as heretical, or ''bid'ah''-literally meaning "innovation" (since the religion is considered to have been perfect when revealed, so anything added later would make it less perfect; "bid'ah" outside of religion is OK, although usually other terms are used).

** Sufism. A rather loose term for sects than put more emphasis upon the spiritual experience and, usually, are less strict on religious laws. It might have been influenced by Hindu mysticism. Sufi imams have considerably greater influence on their followers than the mainstream imams. Their departure from what mainstream Muslims consider within bounds varies, and reactions from mainstream Muslims vary between "that is actually kind of legitimate, even if I don't exactly agree" to "let those eccentrics be" to "those are pseudo-Islam, exterminate them." The first attitude is most common among poorer, less educated Muslims, since Sufism is similar to the folk Islam they practice (loaded with saints and shrines and so on), while higher-class/more educated Muslims tend to gravitate toward the second interpretation (essentially regarding Sufism as a somewhat overblown but still basically orthodox and more or less harmless version of folk Islam), and the ultra-purist Wahhabis love knocking down Sufi sites whenever they get a chance.

* And finally, all three of the Abrahamic religions "tolerate" (or not) each other to various degrees, they only thing they can agree on being their mutual distaste of polytheism.[[note]]And even that is not consistent. Some Christians-historical Catholics, at that-and Jews don't mind the existence of other gods so long as theirs is regarded as the top dog and the focus of worship[[/note]]

* The original Nazarene sect was considered a heresy in Judaism. Once they started recruiting non-Jews without putting them through the proper conversion, Christianity became a distinct religion. (Modern Messianic Judaism, or groups who claim to be Jews who believe Jesus is the messiah, is still considered a heresy and more or less a form of Christianity dressed up as Judaism.) What sealed the break was the expelling of the Christians from the synagogues in AD 82. Up until this point, relations were tense, but it was still a common practice for an Israelite Christian to go to the synagogue on Sabbath morning, and then go home, rest up, and attend Mass in the evening. After the expulsion, Christians no longer regarded themselves as a sect of Judaism, even if they were born Jews.

* Orthodox Judaism, which was codified by the rabbis who wrote Literature/TheTalmud after the Second Temple in Jerusalem was destroyed by the Romans and the Jews were forced into exile, sees itself as the true Jewish religion in an unbroken tradition going back to Moses himself. (Other Jewish sects that existed around that time, like the Essenes and Zealots, have long since died out.) For most of the last two millennia it more or less was the only form of Judaism, other than the Karaites, and is still the sect with the most members. In the last couple of centuries other Jewish denominations have come into being like Conservative Judaism (which is traditionalist like Orthodox Judaism, but not as strict), Reform Judaism (which is progressive and not strict about Jewish law) and Reconstruction Judaism (which sees Judaism as less of a religion and more of a culture). Orthodox Judaism sees all of these as heresies, and conversions to them are not accepted by Orthodox rabbis, but they may still be seen as 'ethnic' Jews who can return to Judaism at any time if they undergo a proper conversion. Orthodox and Conservative Jews tend to agree on more and get along better than Orthodox Jews do with Reform or Reconstruction Jews, who tend to agree more with each other.

* The original Nazarene sect was considered a heresy in Judaism. Once they started recruiting non-Jews without putting them through the proper conversion, Christianity became a distinct religion. Modern Messianic Judaism is considered a heresy. What sealed the break was the expelling of the Christians from the synagogues in AD 82. Up until this point, relations were tense, but it was still a common practice for an Israelite Christian to go to the synagogue on Sabbath morning, and then go home, rest up, and attend Mass in the evening. After the expulsion, Christians no longer regarded themselves as a sect of Judaism, even if they were born Jews.
* Karaism is a sect of Judaism that rejects the [[Literature/TheTalmud Oral Law]], and accepts only the [[Literature/TheBible Written Law]]. There are still a handful around today.
* The Essenes were a sect contemporary with Jesus that believed in a spiritual war between good and evil. They are best known for writing the Dead Sea Scrolls. ([[JustForFun/IThoughtItMeant No]], not [[Anime/NeonGenesisEvangelion those]].)

** In Galileo's day, heliocentrism was actually gaining [[DepartmentOfRedundancyDepartment considerable consideration when considering]] the motion of the stars from an earthly perspective. A Catholic cleric up in Poland[[note]]We won't get into whether he was Polish--Wiki/TheOtherWiki has that covered--but he was definitely working in Poland (his main observatory in Frombork was ''de facto'' in the Polish part of Poland-Lithuania).[[/note]] named Nicolaus Copernicus (for whom is named "The Copernican Revolution") famously brought heliocentrism into vogue. He wrote a long text on the subject, ''On the Revolution of the Celestial Orbs'', but put it into the care of a Protestant friend to be published after his death (the book, which contains an excellent account of heliocentricity, was dedicated to Pope Paul III). The friend, a Lutheran clergyman named Andreas Osiander, anticipated the massive ramifications this theory had for Protestant scriptural interpretation (Martin Luther seemed to condemn the new theory[[note]]Luther calling Copernicus an "upstart astrologer" probably didn't help.[[/note]]) and, the likelihood that it might be condemned; to counter this, Osiander prefaced the book with the claim that the descriptions within were theoretical only, and were only employed to simplify computations... something Copernicus never intended.

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[[folder: Joan of Arc]]

[[folder: Other Christian sects/General Mainstream Christianity]]

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