Docetism and Gnosticism are concepts that were introduced in the early church. These ideas did not have Biblical support, but were familiar to the beliefs and traditions at the time.
Docetism was the first un-bliblcal belief concerning the nature and person of Christ. It arose in the apostolic era and continued to the end of the 2nd Century. The word Docetism is taken from a Greek word meaning “to appear.”
Docetism main concept was that Christ only appeared to have a body, that He was a phantom and not a man. It was adopted by the Ebionites (Jewish Christian) and the Gnostics (Gentile Christians).
Gnosticism was a mix of different pagan philosophies cloaked under Christian terminology. Tradition points Simon Magus (Acts 8:9–24) as the first advocate of this fallacy and the first Christian Gnostic. Later on, Cerinthus promoted these heresies in Alexandria.
The Ebionites were not Gnostics but held similar views concerning the humanity of Christ. They considered Jesus as only the literal son of Joseph. And that He was chosen by God as the Messiah because He was pious and later was adopted as the Son of God at His baptism.
One group of Ebionites, was the Elkesaites, these preached that Christ had been literally “begotten” of the Father in times past, and was therefore lesser than Him. Where the Ebionites considered Jesus as elevated human being, the Gnostics denied that He was a human being.
During the first half of the 2nd century, various Gnostic teachers arose to corrupt the church in Alexandria such as the Basilides and Valentinus. But the most prominent one was Marcion who taught that the birth, life, and death of Jesus were not real, but only an appearance to reality.
The early church fought against these fallacies. Paul warned the Christians in Colossae in 62 AD against Docetic error (Col. 2:4, 8, 9, 18). Peter uttered the same warning (2 Peter 2:1–3). And Jude pointed to the Docetic heresy (v.4).
Irenaeus wrote in the 2d centaury that the apostle John recorded his Gospel to disprove the Docetic views of Cerinthus (Irenaeus Against Heresies xi. 1, in Ante-Nicene Fathers, Vol. 1, p. 426; John 1:1–3, 14; 20:30, 31). And in his epistles, the apostle taught against the Docetic and names its promoters as “anti-christ” (1 John 2:18–26; 1 John 4:1–3, 9, 14; 2 John 7, 10). Also, in the book of Revelation, he spoke against “Nicolaitanes” (Rev. 2:6) who were Gnostics (Irenaeus Against Heresies xi. 1, in Ante-Nicene Fathers, vol. 1, p. 426).
Then, Irenaeus Himself exposed these heresies and stressed the unity of God in his famous work “Against Heresies,” which has survived to our modern days.
In His service,