Marcionism was a religious movement based on the teachings of the 2nd-century heretic Marcion of Sinope. While none of Marcion’s writings have survived to the present, we know of his teachings through several early Christian writers including Justin Martyr (AD 100—165), Irenaeus of Lyons (AD 130—200) and Hippolytus (AD 170—235). These men combatted Marcion in defense of the truth.
Marcion held to many errant views, but he is primarily known for his belief that the Old Testament Scriptures were not authoritative for a Christian. He denied that the God of the Old Testament was the same God presented in the New Testament. For Marcion, Jesus was the Son of the God of the New Testament but not the Son of the deity described in the Hebrew Scriptures. The deities of the Old and New Testaments were, from Marcion’s perspective, literally two different gods. Marcion did not deny the existence of the god of the Old Testament (what he referred to as a Demiurge). He simply classified this god as a secondary deity, one that was inferior to the supreme God revealed in Jesus.
Marcion held that Jesus was the only revelation of the Supreme God but that Jesus should not be seen as having fulfilled Old Testament messianic prophecies. Rather, Marcion saw the prophecies as predicting a yet-to-come earthly savior of the Jewish nation. What Marcion was endorsing was a radical discontinuity between Old Testament Judaism and the message of Jesus and the apostle Paul. Marcion also affirmed a form of Docetism, a view that Jesus was not truly a man but only appeared to be human. This in spite of the clarity of verses such as John 1:14 and 1 John 4:1–3, which speak plainly of Jesus’ true humanity.
After being expelled from the church in Rome in AD 144 for his unorthodox teachings, Marcion formed several of his own churches, many of which retained a church government similar to the orthodox Christian churches of the time. From there, Marcion’s views began to spread. Given Marcion’s complete separation of the God of the Hebrew Bible from the God revealed in Jesus, it should be no surprise that he also rejected the authenticity of many New Testament documents. Any apostolic writing that did not comport with his theories was eliminated until all that remained of his collection of authoritative books were ten of Paul’s letters (minus 1 and 2 Timothy and Titus) and a highly edited version of the Gospel of Luke. Marcion saw Paul as the only legitimate apostle, but even Paul’s writings suffered under Marcion’s scalpel. Any passage that identified the God of the Old Testament with the Father of Jesus was removed. While it is true that most New Testament books were recognized as Scripture from a very early date, it is likely that Marcion’s truncated canon forced the church to more precisely list which books carried apostolic authority.
Marcionism was one of the earliest rivals to the Christian church. The lesson to be learned from Marcionism is that we have no right to act as editor of God’s Word, but we must accept and believe the “whole counsel of God” (Acts 20:27) and “contend for the faith that was once for all entrusted to God’s holy people” (Jude 1:3).