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According to Justin, Marcion was alive ca. 150-155 when he was writing.
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And there is Marcion, a man of Pontus, who is even at this day alive, and teaching his disciples to believe in some other god greater than the Creator. And he, by the aid of the devils, has caused many of every nation to speak blasphemies, and to deny that God is the maker of this universe, and to assert that some other being, greater than He, has done greater works.
Marcion is the author of the Antitheses, and Marcion was active in the first half of the second century.
Against Marcion drew on the Antitheses. In Against Marcion 4.4, it is written:
For if the Gospel, said to be Luke's which is current among us (we shall see whether it be also current with Marcion), is the very one which, as Marcion argues in his Antitheses, was interpolated by the defenders of Judaism, for the purpose of such a conglomeration with it of the law and the prophets as should enable them out of it to fashion their Christ, surely he could not have so argued about it, unless he had found it (in such a form).
There are a few possibilities:
(1) No statement on this topic whatsoever goes back to the Antitheses.
(2) A statement about Luke's gospel doesn't go back to the Antitheses.
(3) A statement about Luke's gospel does go back to the Antitheses, but both Luke and the Gospel used by Marcion were too old for Marcion to know anything about the composition of either.
(4) A statement about Luke's gospel does go back to the Antitheses, and Marcion's Gospel was his own.
(5) A statement about Luke's gospel does go back to the Antitheses, Luke's gospel was recent, and Marcion knew about its origin.
Concerning which:
I find (1) hard to accept, partly because of the new evidence from Origen's Homilies on Psalms and my perusal of Origen's other work. Origen's knowledge of Marcion, concern for refuting Marcion, and vast learning argues strongly that Origen read the Antitheses, similar to how Origen likely read Basilides, Heracleon, and others also. Origen says that Marcion believed there were interpolations in the texts that would be accepted as scripture (including the gospels): viewtopic.php?f=3&t=11986
(2) is possible. It's possible that a statement about "the Gospel" being interpolated goes back to Marcion's Antitheses but that Marcion said nothing specifically on Luke. This is how I used to read it. However, if Luke was pre-130, then this raises the likelihood that Marcion knew Luke. And if Marcion knew Luke, then Marcion would know how much material is common with the gospel he used, making it ripe for comment. If (2) is true (which I consider possible but now don't consider likely), and if Marcion's statement in the Antitheses on the topic didn't include Luke, then Luke was probably unknown to Marcion when he was writing Antitheses.
(3) is plausible. Perhaps both the Gospel that Marcion used and Luke went back to the first century or very early in the second. If (3) is true, then Marcion is not the author of the Gospel that he used, but the literary relationship between the two is unclear.
(4) is possible, but it does not seem very plausible. If Marcion were the author of the Gospel, then on this possibility, by pointing out the so-called interpolations in the known gospels that were previously received, he would be in effect advertising the way that the created his new text by editing the existing ones for speculative restoration of the Gospel. Such a thing would be without parallel in the second century. It would run counter to the implicit goal of winning support for the antiquity of such a new Gospel, which is why most other second century gospels don't do this and simply claim authorship by an apostle.
(5) is more than plausible. If Luke's creation was during the lifetime of Marcion, then it's probable that Marcion would know that the Gospel of Luke was not an ancient text. Given the long life of Marcion as suggested by Justin and Clement, he was in a position to know. The other most plausible alternative is (3), according to which Luke and the gospel that he used were written too long ago for Marcion to know.
In short, I would consider that it's most plausible or likely that:
(3) Both Luke and the gospel that Marcion used were written too early for Marcion to know when either were written.
or
(5) Luke was written recently, during the lifetime of Marcion, and Marcion knew that.
It's also possible (within the margin of a "reasonable doubt") that:
(2) The Antitheses didn't actually say anything about Luke (but see above), which would be most likely in the case that Luke was unknown to Marcion when writing the Antitheses.
(4) Marcion knew that his gospel was recently created and used Luke despite his comments in the Antitheses (but see above).