One of the most important insights of my Marcion and the Dating of the Synoptic Gospels (2014) was the discovery that Marcion’s Gospel existed in two different versions, first as a pre-published, presumably stand-alone draft, and secondly as a published edition with the framing of the Antitheses and the 10 Pauline Letters. How did I derive to this conclusion? The key text in this respect is Tertullian, Adversus Marcionem IV 4,2 which, in a second step, I’d like to put into the broader frame of Tertullian’s discussion of Marcion’s Antitheses and his Gospel in Adversus Marcionem IV 1-5, so that we can follow Tertullian’s arguments. Here, first the crucial passage from Adversus Marcionem IV 4,2:
Quam absurdum, ut, si nostrum antiquius probaverimus, Marcionis vero posterius, et nostrum ante videatur falsum quam habuerit de veritate materiam, et Marcionis ante credatur aemulationem a nostro expertum quam et editum; et postremo id verius existimetur quod est serius, post tot ac tanta iam opera atque documenta Christianae religionis saeculo edita, quae edi utique non potuissent sine evangelii veritate, id est ante evangelii veritatem.
I add the English translation of Ernest Evans of 1972 (Oxford):
How preposterous it would be that when we have proved ours the older, and that Marcion's has emerged later, ours should be taken to have been false before it had from the truth material <for falsehood to work on>, and Marcion's be believed to have suffered hostility from ours before it was even published: and in the end <how ridiculous> that that which is later should be reckoned more true, even after the publication to the world of all those great works and evidences of the Christian religion which surely could never have been produced except for the truth of the gospel—even before the gospel was true.
And the German translation of Karl Adam Heinrich Kellner (BKV, Köln, 1882):
Wenn wir erwiesen haben, dass unser Evangelium älter, das Marcionitische dagegen jünger sei, so wäre es höchst absurd, dass einerseits unser Evangelium schon als ein gefälschtes erscheinen sollte, bevor ein echtes ihm den Stoff dazu geliefert hatte, andererseits das Marcionitische durch das unsrige Widerspruch erfahren habe, bevor es herausgegeben war, und endlich drittens, dass das in höherem Grade als echt gelten soll, was spätern Ursprungs ist, nachdem bereits so viele wichtige Werke und Urkunden der christlichen Religion im Laufe der Zeit erschienen waren, die ohne ein echtes Evangelium, d. h. vor einem echten Evangelium, nicht hätten erscheinen können.
According to the New Testament scholars James Carleton Paget and Frederik Mulders, referring to the quoted passage, ‘the Latin clearly states that Marcion accused the “upholders of Judaism” of having falsified Luke, not of having falsified his own Gospel’.
It seems that such reading is informed by Tertullian’s own interpretation of Marcion’s views, but it is incorrect, if one takes Marcion’s perspective, as given by Tertullian (whether or not historically correct). So, let us explore the passage in more detail:
Tertullian points out that he has ‘proved’ his Gospel to be the older, compared to the Gospel of Marcion, as ‘Marcion’s has emerged later’. While Tertullian is certainly referring to Luke here, in reality in Adversus Marcionem he is mostly working with Matthew. Whichever is meant (we will later see, Tertullian, by using the singular ‘nostrum’ is aggregating here the four later canonical Gospels), Tertullian adds against Marcion that it would be ‘preposterous’ (Evans), or ‘absurd’ (Kellner) (absurdum) if his Gospel ‘should be taken to have been false’ (‘als ein gefälschtes erscheinen sollte’ = should look as if it were plagiarism). Up to this point, there is no mention made about ‘upholders of Judaism’ who have ‘falsified Luke’, but Marcion is being referred to as having claimed that Tertullian’s Gospel looked like a ‘false’ one, a plagiarising one (videatur falsum). The nature of that ‘falsity’ or ‘plagiarism’ is now being further detailed by Tertullian who is still relating Marcion’s argument: ante … quam habuerit de veritate materiam, rendered by Evans as ‘before it had from the truth material’ and by Kellner ‘bevor ein echtes ihm dazu den Stoff geliefert hätte’. This section has been overlooked by Carleton Paget and Mulders, as Marcion is supposed to claim here that a) his own Gospel he regarded as the true one (verum), while he saw the Gospel of Tertullian as the false one (falsum), and c) that the falsity was a form of plagiarism of Marcion’s, as the false Gospel had taken material (Evans) or the material (Kellner: ‘den Stoff’) from the true one. With Evans explanatory addition ‘for falsehood to work on’ is only the nature of the plagiarising redactor further detailed.
Now, the next claim of Marcion, referred to by Tertullian, is even further explicating the nature of this plagiarism: ‘Marcion’s [Gospel] be believed to have suffered hostility from ours’ (Kellner: ‘das Marcionitische durch das unsrige Widerspruch erfahren habe’) (Marcionis ante credatur aemulationem a nostro expertum).
In whichever way one wants to translate ‘aemulatio’, be it by ‘hostility’ (Evans), ‘Widerspruch’ (Kellner), with Lewis and Short’s dictionary as ‘an assiduous striving to equal or excel another in any thing, emulation’, or with Cicero a ‘defective emulation which is similar to rivalry’, it is clear that Marcion believed, the Gospel of Luke (and, as we will see from Tertullian’s report, also the other later canonical Gospels) to be a bad copy of his own, a copy from which is own true Gospel had suffered (Evans) or was even contradicted (Kellner).
As important as this information is the further detail of when such copying and suffering or contradicting took place. Tertullian adds in his report: ante … quam et editum, rendered by Evans as ‘before it was even published’, by Kellner as ‘bevor es herausgegeben war’, the subject of this sentence being ‘Marcionis [evangelium]’. And although Kellner misses to translate the ‘et’, both translators agree that according to Marcion (as reported by Tertullian), he had complained that the false Gospel of Tertullian had taken (Kellner: its) material from Marcion’s true one, even before Marcion had published his true Gospel.
And Tertullian is giving the ultimate point of Marcion’s claim, namely that this Gospel ‘should be reckoned more true, even after the publication to the world of all those great works and evidences of the Christian religion’ (Kellner: ‘dass das in höherem Grade als echt gelten soll, was spätern Ursprungs ist, nachdem bereits so viele wichtige Werke und Urkunden der christlichen Religion im Laufe der Zeit erschienen waren’): postremo id verius existimetur quod est serius, post tot ac tanta iam opera atque documenta Christianae religionis saeculo edita.
According to this third and ultimate point, Marcion is said to have made the – for Tertullian certainly highly absurd – claim that his Gospel was the true one, despite the fact that it was published lately (quod est serius) compared to the publication of those opera atque documenta of the Christian religion, by which he means the later canonical Gospels.
Having gone through this text, it is clear that according to Marcion’s view, his own, the true Gospel, stood at the beginning, on the basis of which the alteration was made, a bad copying of and a taking of material from his own Gospel. This plagiarism had taken place, even before he had published this text. And yet, he maintained that because of the plagiarised nature of the other works and documents, his own Gospel remained to be the true one, despite those others having been published before he himself did publish his own, as we know, by adding to it the Antitheses in which precisely he made those claims, as Tertullian in Adversus Marcionem IV 1-4 first comments on Marcion’s Antitheses. As a second defense of his Gospel, Marcion, only now also seems to have added the collection of 10 Pauline Letters to flag up the consistency between his Gospel and the Gospel of which Paul spoke in his writings.
 The interpretation of which in my Marcion and the Dating of the Synoptic Gospels (2014) had been criticised by James Carleton Paget and Frederik Mulders. See James Carleton Paget, 'Marcion and the Resurrection: Some Thoughts on a Recent Book', Journal for the Study of the New Testament 35 (2012), 74-102 and Frederik Mulders, in his impressively well documented and carefully edited blog (http://resurrectionhope.blogspot.co.uk/2012/08/markus-vinzents-questionable.html).
 J. Carleton Paget, ‘Marcion and the Resurrection: Some Thoughts on a Recent Book’ (2012), 94 n. 47, also quoted by Frederik Mulders in the before mentioned blog entry.
 The German translation of ‘Marcionis’ with ‘Marcionitische [Evangelium]’ is, of course, imprecise and already an interpretation, based on the assumption of the Gospel not being that of Marcion, but only of Marcionite use or character.
 On Kellner’s tendentious translation of Marcionis with ‘Marcionitische’, see the above note.