Whatever or whoever 'Marcion' was, it is terribly unfortunate that our earliest witnesses to him are now preserved almost exclusively in Latin - Irenaeus and Tertullian. For instance when Tertullian writes:
alioquin certi Marcionem dispares deos constituere, alterum iudicem, ferum, bellipotentem, alterum mitem, placidum et tantummodo bonum atque optimum [Against Marcion 1.6]
it is unclear what technical terminology was used by the sect to describe the godhead. We know for instance that the Marcionites identified Jesus as 'Chrestos' from the inscription at Deir Ali. Such physical evidence is very important. Yet the reports of the Church Fathers don't even so much as reference this terminology. The Dialogues of Adamantius for instance are preserved in Greek and the terms ὁ χρηστὸς θεός or even χρηστὸς are never used.
To this end, I think it something of a misrepresentation to argue that the Marcionite identification of Jesus as ὁ χρηστὸς θεός was in itself 'heretical.' As we have already seen from the writings of Philo that it was in fact quite typical of the Alexandrian Jewish worldview to understand that there were two divine powers - one of mercy (θεός) and the other of judgment - and where the former was often referenced as ὁ χρηστὸς θεός. Yes, to be certain Irenaeus criticizes Marcion for also divided the godhead after the Alexandrian fashion. Nevertheless, one must assume that the Jesus of the Alexandrian community as a whole was ὁ χρηστὸς θεός (= the kind God) up to the beginning of the third century. The Origen doesn't use this terminology isn't significant as Origen was something of a renegade.
What made the Marcionites heretical was the emphasis that the Father of the Good Son was τοῦ ἀγαθοῦ θεοῦ (= the Good God). This becomes perfectly clear from the writings of Clement of Alexandria. The other Church Fathers garble the actual formula - perhaps deliberately - or perhaps owing to their unfamiliarity with the true beliefs of the Marcionite community.
It wasn't then that the Marcionites believed that Jesus was 'kind' or even 'the kind power' of the godhead but rather the sectarian belief that the Israelites of previous generations had never known the Father, τοῦ ἀγαθοῦ θεοῦ. This is the crux of the controversy between Marcionites and the Catholics. Clement notes that the Marcionites put the distinction between the gospel and the Pentateuch in that Abraham saw Jesus (= theos, the merciful power) but did not know the Father whom Clement says the Marcionites calls τοῦ ἀγαθοῦ θεοῦ.
But were they to say that the visit of the Saviour was necessary, then the properties of nature are gone from them, the elect being saved by instruction, and purification, and the doing of good works. Abraham, accordingly, who through hearing believed the voice, which promised under the oak in Mamre, “I will give this land to thee, and to thy seed,” was either elect or not. But if he was not, how did he straightway believe, as it were naturally? And if he was elect, their hypothesis is done away with, inasmuch as even previous to the coming of the Lord an election was found, and that saved: “For it was reckoned to him for righteousness.” [Gen. xv. 6; Rom. iv. 3]. For if any one, following Marcion, should dare to say that the Creator saved the man that believed on him, even before the advent of the Lord, (the election being saved with their own proper salvation); the power of the good Being will be eclipsed; inasmuch as late only, and subsequent to the Creator spoken of by them in words of good omen, it made the attempt to save, and by instruction, and in imitation of him. But if, being such, the good Being save, according to them; neither is it his own that he saves, nor is it with the consent of him who formed the creation that he essays salvation, but by force or fraud. And how can he any more be good, acting thus, and being posterior? But if the locality is different, and the dwelling-place of the Omnipotent is remote from the dwelling-place of the good God; yet the will of him who saves, having been the first to begin, is not inferior to that of the good God.
δὲ ἀναγκαίαν τὴν ἐπιδημίαν τοῦ κυρίου φήσαιεν, οἴχεται αὐτοῖς τὰ τῆς φύσεως ἰδιώματα, μαθήσει καὶ καθάρσει καὶ τῇ τῶν ἔργων εὐποιίᾳ, ἀλλ' οὐ φύσει σῳζομένης τῆς ἐκλογῆς. ὁ γοῦν Ἀβραὰμ δι' ἀκοῆς πιστεύσας τῇ φωνῇ τῇ ὑπὸ τὴν δρῦν τὴν ἐν Μαμβρῇ ἐπαγγειλαμένῃ σοὶ δίδωμι τὴν γῆν ταύτην καὶ τῷ σπέρματί σου ἤτοι ἐκλεκτὸς ἦν ἢ οὔ; ἀλλ' εἰ μὲν οὐκ ἦν, πῶς εὐθέως ἐπίστευσεν οἷον φυσικῶς; εἰ δὲ ἦν ἐκλεκτός, λέλυται αὐτοῖς ἡ ὑπόθεσις, εὑρισκομένης καὶ πρὸ τῆς τοῦ κυρίου παρουσίας ἐκλογῆς καὶ δὴ καὶ σῳζομένης· ἐλογίσθη γὰρ αὐτῷ εἰς δικαιοσύνην. ἐὰν γάρ τις τολμήσας λέγῃ Μαρκίωνι ἑπόμενος τὸν δημιουργὸν σῴζειν τὸν εἰς αὐτὸν πιστεύσαντα καὶ πρὸ τῆς τοῦ κυρίου παρουσίας ἐκλογῆς καὶ δὴ καὶ σῳζομένης τὴν ἰδίαν αὐτοῦ σωτηρίαν, παρευδοκιμηθήσεται αὐτῷ ἡ τοῦ ἀγαθοῦ δύναμις, ὀψὲ καὶ μετὰ τὸν ὑπ' αὐτῶν εὐφημούμενον δημιουργὸν ἐπιβαλλομένη σῴζειν καὶ αὐτὴ ἤτοι μαθή σει ἢ καὶ μιμήσει τούτου. ἀλλὰ κἂν οὕτως ἔχων σῴζῃ κατ' αὐτοὺς ὁ ἀγαθός, οὔτε τοὺς ἰδίους οὔτε μετὰ τῆς γνώμης τοῦ πεποιηκότος τὴν κτίσιν ἐπιχειρεῖ τὴν σωτηρίαν, βίᾳ δὲ ἢ δόλῳ. καὶ πῶς ἔτι ἀγαθὸς ὁ οὕτως καὶ ὕστερος; εἰ δὲ ὁ τόπος διαφέρει καὶ ἡ μονὴ τοῦ παντοκράτορος λείπεται ἀπὸ τῆς τοῦ ἀγαθοῦ θεοῦ μονῆς, ἀλλ' ἡ τοῦ σῴζοντος βούλησις οὐκ ἀπολείπεται τοῦ ἀγαθοῦ ἥ γε προκατάρξασα [Strom 5.1]
Let me reiterate the significance of this discovery. We have already demonstrated that in Genesis 17 Clement identified Chrestos as visiting with Abraham and Clement says it was Jesus. Now Clement cites Genesis 12 and 15 (both θεός passages in his LXX, the original Greek translation of the Pentateuch). I think this is the great secret of the Marcionite community. The Alexandrian and Marcionite churches understood the Son (= Jesus Chrestos) to have visited humanity already once but only revealed the Father (= τοῦ ἀγαθοῦ θεοῦ) in the gospel narrative.
As noted I went through the whole of Adamantius's Dialogues and nowhere in the text does the term χρηστὸς let alone ὁ χρηστὸς θεός appear in the text. This couldn't have been what distinguished the Marcionites from 'orthodoxy' in this part of the world (whatever that was). The terminology τοῦ ἀγαθοῦ θεοῦ appears here a number of times as well as other anti-Marcionite texts. The Deir Ali inscription makes clear that Jesus was ὁ χρηστὸς θεός and τοῦ ἀγαθοῦ θεοῦ must have been a title of his Father. As such it is terribly significant that we see Megethius the Marcionite explains the concept of τοῦ ἀγαθοῦ θεοῦ in the Dialogues:
MEG: Although they were bad, the Good God rescued humankind from the Evil One, and then changed and made good those who had believed in Him.
AD. Since you claim that the Good God rescued and changed mankind into goodness, tell us, then, what it was the Good God came to save: soul and body, or only the soul? God?
MEG. Only the soul.
AD. Does the soul belong to the Good God, or to the Creator God?
MEG. The soul is a breath of the Creator God; so when He had created it, He saw that it was evil and disobedient, and cast it out. But the Evil One noticed the soul cast out, and brought it back to himself. However, the Good God had mercy and rescued the soul from the Evil One.
AD. After He had rescued the soul from the Evil One, did the Good God give it to the Creator God, or retain it himself?
Pretty, the English translator of the Dialogues notes in the footnotes to this reference that "in this passage, and in two others (p. 80, "The Good God saves those who believe in Him"; and p. 104, "The Good God is the Father of those who believe"), the ideas of Megethius and Marcus on saving raith are brought to view." I think there can be no doubt that 'the Good God' (= τοῦ ἀγαθοῦ θεοῦ) is the Father and Jesus ὁ χρηστὸς θεός. The term τοῦ ἀγαθοῦ θεοῦ also shows up as a Manichaean terminology too.
