What I have always suggested is that 'things written in the middle of the second century' (Justin) were 're-calibrated' at the end of the second century (Irenaeus) and then that orthodox text was slightly 'polished' again and translated in Latin by Tertullian. The clearest and least controversial example can be traced with respect to Tertullian's Against the Valentinians. This text is a Latin reshaping and translation of an original portion of Irenaeus's Against Heresies Book One a work which originally found inspiration and origin in Justin's Syntagma against the heresies. A footprint of a possible association of Against Marcion with Justin can be found in the fact that Irenaeus references such a text in Against Heresies. It is there also where Irenaeus in another section makes reference to his intention to write a treatise against Marcion which generally resembles Tertullian's end product. Perhaps most interesting of all Tertullian prefaces Against Marcion with the acknowledgement that the 'final text' he is releasing began as an orthodox text but fell into the hands of an apostate and was re-worked again by himself in order to purge it of 'errors.' This introduction may have been written by Tertullian or Irenaeus -at least in theory.
Of course Tertullian loved and admired both Justin and Irenaeus and says so much in one of his works. It would not surprising that Tertullian had access to works of both men and effectively reshaped those originals and passed them off as his own. In this thread. I have added a new wrinkle to that understanding by arguing that 'the antitheses' mentioned throughout the early parts of the work are the Matthean antitheses. In order for that meta-argument to make any sense we would have to suppose that Justin's gospel did not have Matthew 5:17 - 45 or at least the core 'antithetical parts' of that argument or at least a version of the commonly held material in a form which is noncontradictorial.
This is paralleled but not identical with Luke's re-calibration of the same material. For instance Bellinzoni's analysis of the material from Justin leads him "to the conclusion that Justin seems to have used ... a carefully composed gospel harmony of elements from Matthew, Mark, and Luke." Scholars have long noticed that Justin's gospel is a harmonized text - i.e. one which appears (at least from the perspective of an assumption of priority of the canonical four) to fuse together bits of Matthew and Luke. While there are innumerable allusions to Matthew 5/Luke 6 fused together in Justin, the antithetical portions of Matthew 5 are never cited.
Yet what is perhaps even more telling about an underlying relationship between Justin and Against Marcion is the fact that we find very similar Matthew/Luke 'coupled' references in both sources which lie at the edges of the Matthean antitheses. I demonstrated in the other thread that AM perplexingly 'draws a line in the sand' with Marcion's 'excision' of Matthew 5:17 from his gospel. This scripture introduces the antitheses in Matthew. While Justin does not cite Matthew 5:17 he does make a harmonized reference to the 'other end' of the antitheses section of Matthew - i.e. Matthew 5:45b/Luke 6:36 - a cluster which is paralleled in AM:
The parallel isn't just a confirmation of the likelihood that AM has some original relationship to Justin - i.e. the harmonized 'coupling' or 'interest' in Matthew 5:45b and Luke 6:36 even where it is peculiar in a text (i.e. AM) which is devoted to the argument that Marcion solely corrupted Luke to make his gospel. There is a clear intimation in AM 17 that Marcion deleted or altered something in the cited scripture from Matthew.And in addition to all this we pray for you, that Christ may have mercy upon you. For He taught us to pray for our enemies also, saying, 'Love your enemies; be kind and merciful, as your heavenly Father is.' For we see that the Almighty God is kind and merciful, causing His sun to rise on the unthankful and on the righteous, and sending rain on the holy and on the wicked; all of whom He has taught us He will judge. [Dial 96]
He it is who now for a second time gives me the name of son, while he brings me to birth not this time as soul but as spirit. Because, he continues, he is kind unto the unthankful and evil. Well done, Marcion. Cleverly enough have you deprived him of rain and sunshine, that he might not be taken for the Creator. Yet who is this kind one (= original GK Chrestos?), who has never been heard of until now? How could he be kind when from him had proceeded no good gifts of this sort of kindness with which <he had acted> who gave us the loan of sunshine and showers without expectation of any return from the human race? This the Creator has done, who in return for all his liberality in works of nature even until now bears with men while they pay their debt of thanksgiving more readily to idols than to himself. Truly kind is he, even with spiritual benefits: for the judgements of the Lord are sweeter than honey and the honeycomb.e He therefore who has here put the ungrateful to rebuke, is he who had the right to find them grateful, and his sunshine and showers you too, Marcion, have enjoyed without gratitude. Your god however had no call to complain of the ungrateful, as he had made no provision for having them grateful. Again when he teaches of mercy and pity he says, Be ye merciful, even as your Father has had mercy upon you.[AM 17]
Moreover it is worth noting that in AM 17 there seems to be an awareness of an underlying Greek terminology in the shared material which isn't evidenced in our surviving gospels - i.e. χρηστός. The Marcionite inscription from Deir Ali makes clear that χρηστός was the name of the unknown Marcionite god. We should pay careful notice that an understanding in the Latin text of AM seems to go back to this very understanding in the section - "Yet who is this kind one , who has never been heard of until now? How could he be kind when from him had proceeded no good gifts of this sort of kindness with which <he had acted> who gave us the loan of sunshine and showers without expectation of any return from the human race?" The manner in which this references isn't explain or developed in any way to make a Latin audience understand what is being said against Marcion suggests that Tertullian simply copied it out of a Greek original.
In other words, the context suggests that the Marcionite gospel had a harmonzed version of Matthew 5:45b/Luke 6:36 where the term χρηστός appeared and was used by the Marcionites to suggest χρηστός was an epithet of the god unknown to the Jews or at least Jews of the second century. Given that χρηστός and χριστός were homonemes in contemporary Greek and were represented in Christian texts with the same nomen sacrum - i.e. χς - one can see a parallel understanding of an underlying and shared harmonized text in Justin where we read in Dial. that χς may have mercy upon you prefacing the same scriptural 'cluster.' This understanding opens the door to an earlier version of AM written by Justin where orthodox and heretical churches were essentially arguing and accusing one another of manipulating a shared harmonized gospel.
Indeed in a second perplexing allusion to Matthew 5:45b in AM we can see how the author of the proto-text of AM essentially drew a line in the sand as it were at the fringes of the 'Matthean antitheses.' Although on the surface at least we should expect that material in chapter 36 of AM would have little to do with the 'Matthean antitheses' given the fact that in our canonical gospels the Question of the Rich Man/Youth appears near the end of the gospel and the Antitheses near the beginning we shouldn't be so certain that the early harmonies followed our canonical order of narratives. Indeed it is here in a pericope which very much has an 'antithetical context' - i.e. Jesus pontificating on the commandments - that we have clear references to both 'fringes' of the Matthean antitheses (i.e. Matthew 5:17 viz. 'the introduction' and Matthew 5:45b 'the conclusion'):
The point here is that - whether or not the order of the harmonized gospel resembled our canonical gospels - we have further evidence that Marcion's antitheses were in fact linked with Matthew's.It is another matter if as a god supremely good, and of his own nature kind, he does not wish even to be worshipped. Who, he asks, is supremely good, except one, that is God? Not as though he has indicated by this that one out of two gods is supremely good, but that there is one only supremely good God, who is for this reason the one supremely good because he is the only God. And indeed he is supremely good,
sending rain upon the just and the unjust, and making his sun to rise upon the good and the bad—bearing with, and feeding, and helping even Marcionites.(Mt 545b) So then when he is asked by that certain man, Good Teacher, what shall I do to obtain possession of eternal life?, he inquired whether he knew—which means, was keeping—the Creator's commandments, in such form as to testify that by the Creator's commandments eternal life is obtained: and when that man replied, in respect of the chief of them, that he had kept them from his youth up, he got the answer, One thing thou lackest; sell all that thou hast and give to the poor, and thou shall have treasure in heaven; and come, follow me. Come now, Marcion, and all you companions in the misery and sharers in the offensiveness of that heretic, what will you be bold enough to say? Did Christ here rescind those former commandments, not to kill, not to commit adultery, not to steal, not to bear false witness, to love father and mother? Or is it that he both retained these and added what was lacking? And yet, even this commandment of distributing to the poor is spread about everywhere in the law and the prophets, so that that boastful keeper of the commandments was convicted of having money in much higher esteem. So then this also in the gospel remains valid, I am not come to destroy the law and the prophets, but rather to fulfil.[Matthew 5:17] At the same time also he relieved of doubt those other questions, by making it clear that the name of God, and of supremely good, belongs to one only, and that eternal life and treasure in heaven, and himself besides, pertain to that one, whose commandments, by adding what was lacking, he both conserved and enriched. So he is to be recognized as in agreement with Micah, in this passage where he says, Hath he then shewed thee, O man, what is good? Or what doth the Lord require of thee but to do justice, to love mercy, and to be prepared to follow the Lord thy God?c For Christ is that Man, declaring what is good[AM 36]