Marcion of Sinope

Marcion of Sinope (/ˈmɑːrkiən, -siən/; Ancient Greek: Μαρκίων Σινώπης; c. 85 – c. 160) was a theologian in early Christianity. Marcion preached that God had sent Jesus Christ, who was distinct from the "vengeful" God (Demiurge) who had created the world. He considered himself a follower of Paul the Apostle, whom he believed to have been the only true apostle of Jesus Christ; his doctrine is called Marcionism. Marcion published the earliest record of a canon of New Testament books.

Early Church writers such as Justin Martyr, Irenaeus, and Tertullian denounced Marcion as a heretic or antichrist, and he was excommunicated by the church of Rome around 144. He published his own canon of Christian sacred scriptures, which contained ten Pauline epistles (including the Epistle to the Laodiceans, while excluding the Pastoral epistles) and the Gospel of Marcion which historically is claimed to be an edited version of the Gospel of Luke. Some modern scholars, such as Matthias Klinghardt, have theorized that Marcion's Gospel was the oldest, although this has been contested.

This made Marcionism a catalyst in the process of the development of the New Testament canon by forcing the proto-orthodox Church to respond to his canon.