Marcion was a native of Sinope, contemporary Sinop, in Asia Minor, and now part of the territory of Turkey. He was a wealthy shipowner; he became a bishop in the Christian church, and a major financial supporter of the Christian movement. A story told by Tertullian and St Irenæus says that Marcion attempted to use his money to influence the Church to endorse his teaching; they refused. Justin Martyr was also among his critics. He was excommunicated by the Church at Rome in 144.
Marcion's teaching was that Jesus Christ revealed to the world an entirely new god, who was different from the god of the Hebrew Bible. According to Marcion, the god of the Hebrew Bible was jealous, wrathful, and legalistic. The material world he created was defective, a place of suffering; the god who made such a world was the bungling or malicious demiurge. Jesus was not the Messiah promised by Judaism; that Messiah was to be a conqueror and a political leader. Rather, Jesus was sent by a god greater than the Creator. His role was to reveal the transcendent god of light and pure mind, different in character from the creator god of the Hebrew Bible. Jesus's god was free from passion and wrath, wholly benevolent; and Jesus was sent to lead believers out of subjection to the limited, wrathful creator god of the Old Testament.
Marcion produced the first Christian canon, or list of the books of the Bible that he considered authoritative. His list, however, was much smaller than that currently recognised as valid by most Christians; he included only the Gospel of Luke, the Acts of the Apostles, and ten of the epistles attributed to St Paul of Tarsus. (He omitted Paul's pastoral epistles addressed to Timothy and Titus.) These books, according to Marcion, were the ones that contained the true teachings of St Paul. He completely rejected the Old Testament, believing and teaching that it should not be part of the Christian Bible and was of no value to Christians. (See Biblical canon.)
Marcion's position is not identical to, but is closely related to, the beliefs called Gnosticism. His thinking, untenable to almost all Christians today, shows the influence of Hellenistic philosophy on Christianity, and the moral critique of the Hebrew Bible from the ethics of Platonism.