Heresy is the act of speaking against the doctrine of an established religious organization, or simply having private beliefs that are not in accordance with the officially-endorsed position. Heresy differs entirely from apostasy.
In early Christianity, heresy was a recurring problem as people pretending to be Christians would advocate doctrines contrary to the Bible. As heresy was seen as a great threat to the church, spurious allegations of heresy were also used by rival ecclesiarchs to attack their enemies. A series of Councils were held to establish official doctrine, in some cases leading to schisms, such as the split between the Roman Catholic and Eastern Orthodox Churches in the eleventh century (1054).
Today, accusations of heresy are not as widespread as they once were, but some Christians may privately consider those of other denominations to be heretics.
Historically, theological points that have proved fertile sources of heretical beliefs include:
- The nature of Christ, i.e. whether he was both God and Man, or one or the other, or something else entirely (e.g. Arianism).
- The soul, whether it exists and what happens to it after death (e.g. Epicureanism).
- What humans have to do to enter Heaven, e.g. whether faith alone is sufficient (e.g. Pelagianism).
- Arguing that religions other than Christianity are pathways to salvation.
Today these questions may seem unimportant and difficult to answer one way or the other, but during the early centuries of the church, countless hours were devoted to Biblical study in search of the truth, and disagreements often led to ostracism, violence and persecution. In Dante's Inferno, heresy is one of only four sins that are punished with fire (the other three being simony, wicked counsel, and violence against God).Conservative Christian historians and apologists are mindful of this statement from the year 1521:
See Hebrews 13:17 and commentaries on Hebrews 13:17
"...there is no one of the heresies which have torn the bosom of the church, which has not derived its origin from the various interpretation of the Scripture. The Bible itself is the arsenal whence each innovator has drawn his deceptive arguments. It was with biblical texts that Pelagius and Arius maintained their doctrines. Arius, for instance, found the negation of the eternity of the Word—an eternity which you admit, in this verse of the New Testament—Joseph knew not his wife till she had brought forth her first-born son; and he said, in the same way that you say, that this passage enchained him. When the fathers of the Council of Constance condemned this proposition of John Huss—The church of Jesus Christ is only the community of the elect, they condemned an error; for the church, like a good mother, embraces within her arms all who bear the name of Christian, all who are called to enjoy the celestial beatitude."
- The Great Heresies list of heresies committed by Catholics: Circumcisers, Gnosticism, Montanism, Sabellianism, Arianism, Pelagianism, Semi-Pelagianism, Nestorianism, Monophysitism, Iconoclasm, Catharism, Protestantism, and Jansenism.
- Exsurge Domine Condemning the Errors of Martin Luther: Pope Leo X - 1520 - Papal Encyclicals Online (papalencyclicals.net) "Wise in their own eyes, according to the ancient practice of heretics, they interpret these same Scriptures otherwise than the Holy Spirit demands, inspired only by their own sense of ambition, and for the sake of popular acclaim, as the Apostle declares. In fact, they twist and adulterate the Scriptures. As a result, according to Jerome, 'It is no longer the Gospel of Christ, but a man’s, or what is worse, the devil’s.' "
- Note to the reader: The numbered statements listed in the document are not the teaching of the Catholic Church, but are specific propositions of Martin Luther condemned by the Catholic Church. In other words, the numbered statements are presented as the actual teachings of Luther against the doctrines of the Catholic Church.
- False Religions: List of Catholic Heresies and Human Traditions Adopted and Perpetuated by the Roman Catholic Church in the course of 1600 years. Rev. Stephen L. Testa (jesus-is-savior.com) The first heresy that Pastor Testa lists is "Wax candles introduced into the church" in the year 320. The selective use of Proof texts in the article is a classic example of Confirmation bias for the purpose of Polemic.
- Note to the reader: In regard to the number 666 as applied to VICARIUS FILII DEI "Vicar of the Son of God" in this article, the name of the woman who started Seventh-Day Adventism, Ellen Gould White, in Latin characters, calculated by the value of Latin characters as Roman numerals, also adds up to 666:
E = 0 — L = 50 — L = 50 — E = 0 — N = 0: = 100
G = 0 — O = 0 — U = 5 — L = 50 — D = 500: = 555 (Latin V is U as in JVLIVS Julius)
W = 10 — H = 0 — I = 1 — T = 0 — E = 0: = 11 (Latin W double-U is VV 5+5 = 10)
100 + 555 + 11 = 666 — Ellen=100, Gould=555, White=11.
Many names total 666. The identity of the Beast of Revelation cannot be established or proven with any certainty by gematria alone. Revelation 13:18 was written in Greek, not Latin, and the numerical value of the Greek letters of the transliterated Latin NRWN QSR (NiRoN QaiSaR), or Nero Caesar, also totals 666, but the Greek letter equivalent transliteration of VICARIUS FILII DEI does not (it totals 1723). This raises the question of which of the more than 200 popes was or is in fact the "man of sin", the "antichrist" and the "beast of Revelation" whose number is the number of a man (one man)—666. “This famous number  has been made to yield almost all the historical names of the past eighteen centuries: Titus, Vespasian, and Simon Giroas; Julian the Apostate and Genseric; Mohamet and Luther; Benedict IX and Louis XV; Napoleon I and the Duke of Reichstadt; and it would not be difficult, on the same principles to read in it one another’s names” (Vincent, Word Studies, vol.11, p.531)—Reuss "The Secret of the Number 666"
And since the time of Reuss, many other names might be added such as Hitler, Mussolini, and a host of others.
See commentaries on 1 John 2:18, 2 Thessalonians 2:3 and Revelation 13:18.
- Are Protestantism and Roman Catholicism Heretical? - Orthodox Christian Information Center (orthodoxinfo.com) "...to help my fellow Orthodox brothers and sisters to understand that much of the rhetoric we hear today regarding Western Christians is not faithful to Holy Tradition. It thus undermines the unity and uniqueness of the one true Church—the Orthodox Church—, which embodies the very criterion of Christianity, being the sole preserver of the unadulterated Apostolic and Holy Tradition."
- Fundamentalist Heretics (thepoorinspirit.com) The author asserts that fundamentalist Christians can go too far, can become extremists, and in doing so become heretics themselves without realizing it.
- Apostasy in the church and false doctrines of men, By Don Koenig (thepropheticyears.com) "Most of the major Christian denominations have deviated from biblical Christianity in one way or another" — Pastor Koenig lists and analyzes the heretical deviations of the following Christian denominations: The Roman Catholic Church, The Orthodox Catholic Churches, The Protestants, The non-Pentecostal Evangelicals, and The Pentecostals.
- Note to the reader: There are self-contradictions in Don Koenig's article, especially the obvious inconsistency in his simultaneously condemning the need for good works, and yet insisting that good works producing fruit are the necessary mark of a true Christian. Of Catholicism he says, "Some in religious training were taught that Jesus died for their sins and that they are saved or justified, but in their lives there is no evidence by works of the Spirit...Those that trust in their own good works to save themselves are self-deceived and still in their sins...Some in this church have found the path to salvation and have been born of the Holy Spirit, but many of these are not producing the fruit that they should." Of Orthodoxy he says, "This institutional church is mostly apostate and the church in general has done few good works on earth." Of Protestants he says, "The biggest cults of Christianity are the Mormons and the Latter Day Saints. The overwhelming majority of the people in the liberal Protestant denominations have never had a born again experience nor do their lives reflect that God is indwelling them." He quotes Revelation 3:2 "I have found no works of thine perfected before my God." But he does not quote Revelation 20:12-13 regarding the fact that Christ will judge each of us according to our works (see also Matthew 7:21-23 and Matthew 25:31-46 in which belief, prayer and church attendance are not mentioned; and Matthew 28:20—compare Antinomianism). And his position against the absolute need for doing good works (ordained by God as necessary for salvation) contradicts the teaching of Paul in Romans 2:6-10 and Ephesians 2:10. (See article Corporal and spiritual works of mercy.) He is also ignorant of the fact that the "cults" (note the plural) of the Mormons and the Latter Day Saints are not two cults but the same thing—The Church of Jesus Christ of Latter-Day Saints. Moreover, unlike Exsurge Domine which exactly states Martin Luther's teaching he falsely misrepresents the doctrines of several of the churches he faults as being apostate and from Satan, saying that they mean what they do not mean, without explaining their actual, official meaning (Straw man fallacy and Putting words in someone's mouth), and he condemns repetitive prayers, a practice which is found approved in the Bible (see for example the repetitive prayer of Psalm 136 "for his mercy endureth for ever" 26 times; also Ephesians 5:19-20, Colossians 3:16, Hebrews 13:15, Luke 18:1-8 the widow and the judge, 1 Timothy 2:1-2, Revelation 8:3-4, Hebrews 12:22-23, Matthew 22:31-32, Revelation 12:1 Queen of heaven, Luke 1:28 and Luke 1:42-43 and Luke 1:48, also Psalm 45:6-16 and 1 Kings 2:19 with Hebrews 12:22-23—see History of the Rosary: 150 Psalms). And he also demonstrates that he is ignorant of good English usage, spelling and syntax. All of these facts damage his credibility and any claim to be a reliable and informed writer.
- Pastoral Constitution on the Church in the Modern World Gaudium et Spes Promulgated by His Holiness Pope Paul VI on December 7, 1965 (scborromeo.org) pdf Includes analysis of the phenomenon of atheism and disbelief, why and how people turn away from the truth of the Gospel.