Major Christian Heresies
False Doctrines promoted by apostate members of the Catholic clergy
And the Authoritative Persons, Church Councils and Creeds that were formulated to oppose them

    See also: A more complete list of heresies from Catholic Answers

    Arianism was perhaps the most typical and persistent of the ancient heresies. Basically it involved a denial of the divinity of Jesus Christ. Arianism was advanced by Arius (256-336), a priest of Alexandria in Egypt, who denied that there were three distinct divine Persons in the Holy Trinity. Arianism was formally condemned by the First Council of Nicaea in 325.
    Unitarians who believe in a uni-personal instead of a tri-personal God and Mormons who also profess to believe “As man now is, God once was. As God now is, man may become.” are both modern Arian sects.

    Nestorianism was a heresy promoted by a bishop of Constantinople, Nestorius (d. c. 451), who held that there were two distinct persons in Christ, one human and one divine. Thus, the Nestorians claimed that it could not be said that God was born, was crucified, or died. Mary merely gave birth to a man whose human person was conjoined to that of God. The Nestorians saw Christ's divinity as superimposed on his humanity. Nestorianism was condemned by the Council of Ephesus in 431.

    Monophysitism, the heresy opposed to Nestorianism, arose as a corrective to the latter, but it went too far, holding that in Christ there is only one nature, a divine nature. Monophysitism was condemned by the Council of Chalcedon in 451. This great Council taught that Christ was true God and true man, a divine person possessing both a divine and a human nature, thus rounding out the Church's permanent understanding of Christology. The Nicene Creed, which was specificially created at the Council of Nicea (325) to refute Arianism, ended up as a refutation of Nestorianism and Monophysitism as well.

    Donatism was a fourth and fifth century African heresy that held that the validity of the sacraments depended upon the moral character of the person administering the sacraments. The Donatists ended up as a widespread sect that ordained its own bishops, one of whom was Donatus, who gave his name to the movement. Vigorously opposed by the great St. Augustine, Bishop of Hippo-Regius in North Africa (354-430), the Donatist movement persisted in northern Africa until the Muslim conquest in the seventh century.

    Pelagianism, championed by a monk from the British Isles named Pelagius (355-425). Pelagius denied that divine grace in the soul is necessary to do good; his doctrine included a number of heretical tenets such as that Adam would have died even if he had not sinned and that Adam's fall injured only himself.     Essentially, Pelagianism amounted to a denial of the doctrine of original sin, and it also entailed a denial of the supernatural order and of the necessity of divine grace for salvation.
    But nothing is more common in modern thinking than the denial of original sin. Outside the Catholic Church, it is nearly universal, and it persists in the face of all the evidence against it. St. Augustine, who had discovered from bitter personal experience that he could not be chaste without the help of grace, strongly and persistently contested Pelagius and his teaching.

    Gnosticism is the idea that salvation comes through knowledge-usually some special kind of knowledge claimed by an elite. Gnosticism is pseudo-intellectual, and trusts exclusively to special or magical knowledge. Most varieties of Gnosticism also hold that matter and the body are evil while only "spirit" is good. The theory thus denies the truth of the biblical teaching that "God saw that it was good" (Gen. 1:10, 12, 18, 21, 25).
    For the true Gnostic, the Incarnation is a scandal - God would not contaminate his spirit by taking on a body. But true salvation comes uniquely from Jesus Christ: "There is no other name under heaven given among men by which we must be saved" (Acts 4:12). This revelation of salvation in Christ is essentially what Gnosticism denies. Many early Christian Fathers and writers such as St. Justin Martyr (d. c. 165) and Tertullian opposed Gnosticism. Yet another early Church Father and Doctor of the Church, St. Irenaeus, Bishop of Lyons (second century), in his best-known work, Against Heresies, refutes the teachings of the Gnostics.

Justification by Faith Alone or Sola Fide (also refuted here) is viewed as one of the more recent heresies. Sola Fide was attributed to the rebellious German Monk Martin Luther and formulated during the Protestant Reformation in the 16th Century. This novel doctrine opposed the long-held Roman Catholic teaching that faith devoid of charity and good works is a dead faith.

Scripurally refuted by Apostles James and Paul
    (James 2:17 "So also faith of itself, if it does not have works, is dead.")
    (Galatians 5:6 "For in Christ Jesus, neither circumcision nor uncircumcision counts for anything, but only faith working through love.")
    (1 Corinthians 13:2 "if I have all faith so as to move mountains but do not have love, I am nothing.")

    In the Council of Trent, which ran from 1545 to 1563, the Catholic Church would refute this false doctrine of Sola Fide and it's companion doctrine Sola Scriptura (Bible Alone), which was another unscriptural protestant false teaching, which had been originally proposed by the heretic John Wycliffe of England (1328-1384), well over 100 years earlier. Wycliffe's heresies were first condemned at the Council of Constance (1414-1418)

    This false doctrine of Sola Scriptura, sometimes referred to as private judgment and also as biblical perspicuity, (Here and Here, and also Here) has resulted in doctrinal chaos among Christians, which has had a massive negative impact upon Christian worship. It has resulted in the splintering of Christianity, from one Christian Church, into thousands of different Christian denominations and quasi-Christian groups and sects since its inception.
    "This idea is rejected in 2 Peter 1:20, where we are told the first rule of Bible interpretation: 'First of all you must understand this, that no prophecy of Scripture is a matter of one’s own interpretation.' A significant feature of this heresy is the attempt to pit the Church “against” the Bible, denying that the magisterium has any infallible authority to interpret Scripture." (Catholic Answers)

    It does not take a mental giant to realize that Satan must revel in all of the Christian infighting and barb throwing. He must love it when Christians launch unwarranted attacks and criticisms against other Christians since Christianity is supposed to be, above all, the religion of fellowship and love.

Jehovah’s Witnesses are not really a Catholic Hersesy but an anti-catholic (anti-christian) sect founded in 1879 by Charles Taze Russell.
    Among other things (see link) Jehovah's Witnesses believe:
  • That Jesus Christ is not God and was a created being.
  • That Christ is God’s Son and is inferior to him.
  • That there is no Hell, simply annihilation.
  • That taking blood into the body through mouth or veins violates God’s law. (No transfusions!)