Tertullian, Against Marcion 21
If Marcion preaches a new God while trying to shut out the old God's law, why does he lay down not a single rule about this new deity, but only about the old law — unless it's because faith stayed put in the Creator, so that only the Creator's law could still be acknowledged? That very Psalm saw it coming: "Let us break their chains and throw off their yoke" (Psalm 2:3); and sure enough, the nations erupted, the peoples plotted emptiness, earth's kings took their stand, and rulers gathered as one against the Lord and against his Christ.
If Paul had been proclaiming a different God, there would have been zero debate over whether to keep the law — since that law wouldn't pertain to the new Lord and rival of the law in the first place. The sheer novelty and otherness of such a God would have erased not just the question of the old, alien law, but every mention of it. But that wasn't the issue. The whole dispute was this: when the very same God of the law is preached in Christ, why is his law being whittled away? Faith never budged from the Creator and his Christ; what wavered was conduct and discipline.
Some argued over eating idol-meat, some over women's veils, some over marriage or divorce, a few even over the hope of resurrection — but no one argued over God. If that question had been in play, it would have surfaced with the apostle, and how much more urgently. But if truth suffered adultery regarding God's rule after the apostles' time, then the apostolic tradition suffered no such corruption in its own day, and no other apostolic tradition will be recognized than the one published today in their churches.
You will not find a single church on the apostolic roll that does not Christianize in the Creator. And if those churches were corrupted from the start, which ones remain intact? Obviously, the ones opposed to the Creator. So produce one from your apostolic roll, and you'll be refuted. Since it's now established on every front that from Christ to Marcion no other God stood in the rule of this sacrament but the Creator, our proof stands fortified: we've shown the heretic's 'knowledge of God' began by severing Gospel from law, and the definition above holds — you must not believe in a God a man has cobbled together from his own senses, unless he's a prophet; that is, not from his own senses. If Marcion can claim that, he must prove it; nothing will be retracted. For by this wedge of truth all heresy is expelled, once Christ is shown to be the circumciser not of some other God, but of the Creator.
Latin
Ceterum si, qua nouum deum praedicans, ueteris dei legem cupiebat excludere, quare de deo quidem nouo nihil praescribit, sed de uetere lege solummodo, nisi quoniam fide manente in creatorem sola lex eius concessare debebat? ut et psalmus ille praececinerat: disrumpam ua a nobis is uincula eorum et abiciamus eorum iugum a nobis; ex quo scilicet tumultuatae sunt gentes et populi meditati sunt inania, adstitel\'unt reges terrae et magi stratus conuenerunt in unum aduersus dominum et aduersus Christum eius. et utique, si alius deus praedicaretur a Paulo, nulla disceptatio esset seruandae legis necne, non pertinentis scilicet ad dominum nouum et aemulum legis. ipsa enim dei nouitas atque diuersitas abstulisset non modo quaestionem ueteris et alienae legis uerum omnem eius mentionem. sed hic erat totus status quaestionis, quid, cum idem deus legis in Christo praedicaretur, legi eius derogaretur. stabat igitur fides semper in creatore et Christo eius, sed conuersatio et disciplina nutabat. nam et alii de idolothyto edendo, alii de mulierum uelamento, alii de nuptiis uel repudiis, nonnulli et de spe resurrectionis disceptabant, de deo nemo. nam (si) fuisset haec quoque quaestio disceptata, et ipsa apud apostolum inueniretur, uel quanto principalis. quodsi post apostolorum tempora adulterium ueritas passa est circa dei regulam, ergo iam apostolica traditio nihil passa est in tempore suo circa dei regulam, et non alia agnoscenda erit traditio apostolorum quam quae hodie apud ipsorum ecclesias editur. nullam autem apostolici census ecclesiam inuenias, quae non in creatore christianizet. aut si hae erunt a primordio corruptae. quae erunt integrae? nimirum aduersariae creatoris. exhibe ergo aliquam ex tuis apostolici census, et obduxeris. igitur cum omnibus modis constet alium deum in regula sacramenti istius non fuisse a Christo usque ad Marcionem quam creatorem, satis iam et probatio nostra munita est, qua ostendimus notitiam dei haeretici ex euangelii et legis separatione coepisse, et definitio superior instructa est, non esse credendum deum, quem homo de suis sensibus composuerit, nisi plane prophetes. id est non de suis sensibus. quod si Marcion poterit dici, debebit etiam probari; ** nihil retractare oportebit. hoc enim cuneo ueritatis omnis extruditur haeresis, cum Christus non alterius dei quam creatoris circumlator ostenditur.