Adolf von Harnack
The great Adolph von Harnack was a forerunner in both general canonical studies as well as specific considerations of Marcion, with his works setting the tone for the years of scholarship since. His fullest treatment of Marcion came in Marcion: The Gospel of the Alien God, in which he not only treated Marcion’s theology and offered a reconstruction of Marcion’s writings, but also argued that Marcion’s canon became the originator of the later canon of the Great Church. Arguing that Marcion was influenced by the syncretism of an early Christianity formed between the influences of Greek philosophy, Jewish scriptures, Judaism, Greco-Roman syncretism, Jesus’ disciples, and the apostle Paul, Harnack understood Marcion to proclaim God as an alien force at work leading the world out of the oppression of the creator god.  For Marcion, the “Christian concept of God must therefore be stated exclusively and without remainder in terms of the redemption wrought by Christ. Thus God may not and cannot be anything other than the God in the sense of merciful and redeeming love.” Marcion’s novel idea was his rejection of the Jewish scriptures, where the alien nature of the true God was not found, and the implementation of the new books of the gospel and Paul against the old writings. Because the Jewish god could not be understood as the God of Jesus, Marcion concluded that there the writings of Paul included elements of Judaism, they must have been corrupted, as had at least one narrative account of Jesus’ life.
In Marcion: The Gospel of the Alien God, Harnack offered restored versions of the writings within Marcion’s canon based on patristic evidence (primarily Tertullian), Marcion’s theology, and text-critical information available from Western-type texts. The Antitheses Harnack understood to be Marcion’s explanation and quotation of various scriptural passages, both in Jewish and Christian writings, including explanations concerning Judaizing apostles such as Matthew. While Harnack admitted that a reconstruction of the Antitheses was impossible, he concluded that, “The introduction to the Antitheses rejected the four Gospels of the great church as false, traced the apostles and their pupils to Judaism, acknowledged as valid only the apostle Paul,… and identified the gospel with the third gospel which had been directly given to Christ, adultered by Luke, and purged of its Judaistic interpolations.” In this understanding, Marcion’s conception of a God who was far removed from the corruption of the world was necessary to understand the uniqueness of Jesus. Rejecting the corruptions of Jewish scriptures and the Jewish influences on newer Christian writings, Marcion formed a new set of authoritative scriptures, including primarily the writings of Paul, and set them up as a collection of authoritative writings for his church and followers. This new collection of authoritative writings, for Harnack, eventually forced other Christian groups to grapple with questions of which writings were authoritative, finally bringing about a formalized Christian New Testament canon.
 Adolf Von Harnack. Marcion: The Gospel of the Alien God. Translated by John E. Steely and Lyle D. Bierma. Labyrinth Press: Durham, 1990. 3, 8-9.  Ibid., 13.  Ibid., 22-4.  Ibid., 25-9.  Ibid., 30-1, 51. For Pauline reconstructions see 31-6; for Lucan reconstruction see 36-43. Harnack understood Marcion’s revisions to consist primarily of exclusions of material from the text, though he noted several instances were additions and amendments would have likely occurred given his theological perspective, see 43-7. Also noteworthy for our purposes, Harnack argued that Marcion allowed (or even encouraged) his followers to continue refining and clarifying the corruptions within the their scriptural texts. See 30. Further, he notes that Marcion understood Tatian’s Diatessaraon to have been compiled as a reaction to Marcion’s single gospel canon, see 50.  Ibid., 54-6.  Ibid., 57.