This article catalogs some of the movements within early Christianity at variance with the orthodox faith. Material from this guide came from History of the Christian Church by Henry C. Sheldon, the Encyclopaedia Britannica, and A History of Heresy by David Christie-Murray.
Ebionites considered Christianity as a sect of Judaism. The believed the Jesus was a mere man of exceptional righteousness and a superior endowment of the Spirit which came upon him at his baptism. Some Ebionites accepted, and some rejected the supernatural conception of Christ. Ebionites were among the Judaizers who attempted to impose the law of Moses upon Christians. Ebionites were millenialists--those who believe in a literal 1,000-year reign of Christ on Earth.
Cerinthus (contemporary of the Apostle John) combined Gnostic views (separating the earthly Jesus who was the son of Joseph and Mary from the heavenly Christ) with the views of the Judaizers. Cerinthus was also a millinnealist (also known as chiliasm).
Based on on a 2nd century document claiming to be a collection of sermons by Clement of Rome. These writings emphasize the unity of God (as opposed to the Trinity), representing God as dwelling in bodily form at the center of the universe. The work is strongly dualist -- dividing everything into a thing and its opposite (male-female, good-evil, Christ-antichrist, etc.).
Predating Christianity, it is not correct to consider Gnosticism as merely a Christian heresy. Gnosticism may be considered a religion on its own. A syncretistic religion (a religion which borrows freely from and integrates elements of other religions), Gnosticism contains elements of Judaism, Jewish speculation, Christianity, Zoroastrianism and other Mediterranean and Eastern mystery religions. While there are many varieties of Gnosticism, they all shared an elitist view that some people are capable of knowing (hence the word Gnostic from the Greek word gnosis = knowledge) and understanding the secrets and those who were unredeemable. Salvation is a matter of knowledge rather than works or faith.
Gnostics had elaborate systems of heavenly beings and their relationships borrowed from Jewish speculation and such works as the Book of Enoch. Gnostics are strong dualists. They held that there is a Supreme Being, unknowable to the world, from whom unfolded attributes and powers who manifested in personal form. There is a chain of these beings, called AEons, linking the Supreme Being to the material world. "The Savior" was one of the AEons who united himself with Jesus of Nazareth in an un-real incarnation. Mankind is divided into immutable classes--some destined for salvation and some for destruction. Gnosticism was strongest in the 2nd century.
Christian Gnosticism was said to have started with Simon Magus (mentioned in the book of Acts) who represented himself as a manifestation of divinity (the active principle or father of the universe) and his companion, Helena, as the embodiment of the passive or feminine principle (note the dualism).
Carpocrates and later his son Epiphanes (founders of the Carpocroations) considered Jesus equal to other men of religions fame. They were antinomian, teaching that there are no binding moral laws and that contempt for such restrictions is a stepping-stone to emancipation. (Not all Gnostics were antinomian, by any means.) Antinomianism holds that matter is evil and that whatever is material (including immoral acts done in the body) are of no consequence. In extreme forms, immoral acts confirm one belief in the purely spiritual. In a sense antinomianism and asceticism are similar--both denying the body--one through giving the body free reign, and the other by denying it.
Within Gnosticism, there were various systems and teachers:
The unnamable and unknowable Being produces instantly and by fiat a "world seed" which contains the universe in germ and a threefold sonship. The first rises to be the supreme Deity, the second rises to a next inferior place, and the third to the lower regions. From hence come a system of Rulers (one, Abraxas rules 365 heavens). The rulers generated sons, one of whom provided enlightenment for Jesus of Nazareth thereby beginning the ascent of Jesus to higher regions.
Valentinius (teaching between 140 and 160 AD) created probably the most elaborate of the Gnostic systems. For Valentinius, God was the primordial abyss, the absolute ground of all real existence. From the Supreme Father emanates the first pair of AEons, Nous and Aletheia. From these emanate Logos and Zoe and from them Anthropos and Ecclesia. Ten additional emanations from the original pair. The total number of 28 AEons makes constitute the plemora, or the region of light. The perfect harmony of the plemora is broken a lesser AEon, Sophia who wants to emanate without her partner. The result is a formess being unfit for the plemora. In response, the Supreme Being brings forth another pair of AEons, namely Christ and the Holy Spirit. Sophia is tortured by the AEons with desire, fear, grief and perplexity which separates various beings from her, one of whom is the Demiurge, or world-fashioner, the creator of mankind. Mankind is of three orders, earthly, psychical and spiritial.
Jesus (Messiah) was in a bodily form, but was actually composed, in the image of the Demiurge, of etheral material from the upper regions. The Savior, from the plemora, joined Jesus at his Baptism. Jesus brought enlightenment so that the Spiritual men could be received into the company of the angels, psychical men can be happy in the paradise of the Demiurge, and earthly men are destroyed., consumed by fire.
Saturnians believed that there were a regions of light and darkness, the border of which is guarded by seven angels, the chief of which is the God of the Jews. Men were either allied with the powers of light or darkness (Satan). They believed asceticism (the self-denial of the body and its comforts) was the path to freedom. They were celibate and largely vegetarian.
Marcion, the reputed son of a Christian Bishop was a systematic Gnostic teacher and missionary. He denied all doctrinal authority of the Old Testament, and considered the letters of Paul (along with his highly-edited edition of the Gospel of Luke) as the only authority.
Marcion could not reconcile the angry punishing God of the Old Testament with the loving God of the new, so he considered the Old Testament God, Jehovah, as the Demiurge, a middle being between the Supreme God and the material world--Jehovah falsely thinking himself supreme. Men were created by the Demiurge with evil and corrupt bodies. The Demiurge created Jesus in an attempt to save mankind, but the Supreme Being sent Christ (who was not born of Mary) to unite with Jesus.
Marcion was an absolute docetist denying that Christ was material, or that he suffered and died. Marcionites were noted for their personal purity.
Manicheism is more of a religion in its own right than a Christian heresy. Mani, considering himself in the line of Buddha, Zoroaster and Jesus, was executed in the late 3rd century. He encouraged missionary activity. This religion was at it's core a Gnostic sect, believing that matter is evil, but that the human soul is godlike. Salvation comes through knowledge of how things really are.
Monarchianism was a 2nd and 3rd century Christian heresy which took two forms. In Dynamic Monarchianism, it was held that Christ was a mere man, miraculously conceived, who became the Son of God because of the infinite degree to which he had been filled with wisdom and power. Modalist Monarchianism held that the Father and Son are just names for the same person.
Montanus, a 2nd century prophet taught that he himself was the final revelation of the Holy Spirit which Jesus had promised to send. Montanists were strictly and legalistically moral and looked for the imminent second coming of Jesus. Most of the Montanist writings have been lost.
Arius taught in the 4th century that God alone was self-existent and immutable, and therefore the Son must have been a created being. Worship of the Son continued, so that in some sense Arianism was Polytheistic. Arianism was condemned by the Council of Nicaea in 325 AD whose creed rules out this heresy from the orthodox faith.
This Christological heresy followed from the concept of a human being consisting of three separate parts: a body, a soul and a spirit. Jesus, taught Appolonarius, had a human body and soul, but his spirit was the divine Logos. He thought of Christ as God clothed in human flesh.
See Eutychianism.
Eutyches was a 4-5th century monk who taught a form of Monophysitism. "Christ, he maintained, was of two natures, but not in them; before the union there existed the two natures, divine and human, but after it the two so blended that there was one nature only, and that fully divine, Jesus was homoousion [one substance] with the Father but not with man." [Christie-Murray, 69]
Christological heresies spring from an overemphasis on either the human or the divine side of Jesus. Nestorianism is one of the former. The Encyclopaedia Britannica says:
What [Nestorius] actually taught was a prosopic union. The Greek term prosopon means the self-manifestation of an individual that can be extended by means of other things--e.g., a painter includes his brush within his own prosopon. So the Son of God used manhood for his self-manifestation, and manhood was, therefore, included in his prosopon, so that he was a single object of presentation.
Nestorius wrote:
The Church teaches that God the Son was not united to an already existing being but that Christ's human nature, when first created by God, was not given one moment's purely human existence. From the first moment it existed, not as a single independent existing essence or nature, but as the human nature of the Word...It was his nature, not as our garments are our garments but as our hearts are our hearts, united to his eternal Godhead with a union so close that the only analogy we can find is the union in man of soul and body....As the reasonable soul and flesh is one man, so God and man is one Christ.
Pelagius (5th century) denied the doctrine of Original Sin and taught that humans were creatures of essential goodness and free will. He held that sin was voluntary, not the inevitable consequence of human weakness. Pelagius hoped to encourage higher moral standards among Christians.
Unlike the Pelagians, who denied original sin and believed in perfect human free will, the semi-Pelagians believed in the universality of original sin as a corruptive force in man. They also believed that without God's grace this corruptive force could not be overcome, and they therefore admitted the necessity of grace for Christian life and action. They also insisted on the necessity of Baptism, even for infants. But contrary to Augustine, they taught that the innate corruption of man was not so great that the initiative toward Christian commitment was beyond the powers of man's native will.
Encyclopaedia Britannica
Related to Monophysitism, Monothelitism is holds that there is a single will in Christ.