goodness and justice are in such close association and agreement that the separation of one from the other is inconceivable, how can you dare to postulate an opposition between two gods, counting out separately on the one side a good god and on the other side a just one [Adv Marc 2.12]
Almost the same distinction appears in Irenaeus AH 3.25 but even here it shows signs of being tampered with:
Again, that they might remove the rebuking and judicial power from the Father, reckoning that as unworthy of God, and thinking that they had found out a God both without anger and [merely] good, they have alleged that one [God] judges, but that another saves, unconsciously taking away the intelligence and justice of both deities. For if the judicial one is not also good, to bestow favours upon the deserving, and to direct reproofs against those requiring them, he will appear neither a just nor a wise judge. On the other hand, the good God, if he is merely good, and not one who tests those upon whom he shall send his goodness, will be out of the range of justice and goodness; and his goodness will seem imperfect, as not saving all; [for it should do so,] if it be not accompanied with judgment. Marcion, therefore, himself, by dividing God into two, maintaining one to be good and the other judicial, does in fact, on both sides, put an end to deity. For he that is the judicial one, if he be not good, is not God, because he from whom goodness is absent is no God at all; and again, he who is good, if he has no judicial power, suffers the same [loss] as the former, by being deprived of his character of deity. And how can they call the Father of all wise, if they do not assign to Him a judicial faculty? For if He is wise, He is also one who tests [others]; but the judicial power belongs to him who tests, and justice follows the judicial faculty, that it may reach a just conclusion; justice calls forth judgment, and judgment, when it is executed with justice, will pass on to wisdom. Therefore the Father will excel in wisdom all human and angelic wisdom, because He is Lord, and Judge, and the Just One, and Ruler over all. For He is good, and merciful, and patient, and saves whom He ought: nor does goodness desert Him in the exercise of justice, nor is His wisdom lessened; for He saves those whom He should save, and judges those worthy of judgment. Neither does He show Himself unmercifully just; for His goodness, no doubt, goes on before, and takes precedency.
The point is clearly that the original information about Marcion comes from Theophilus and earlier sources. However Irenaeus took over the information and is ultimately responsible for its corruption and misrepresentation.
Elohim and Yahweh are the powers of mercy and judgment respectively according to the original Jewish understanding. At some point the rabbinic tradition transposed (= Lat. antithesis) that understanding. Yawheh became mercy and Elohim judgment. It is clear from another section in the original treatise behind Against Marcion Book Two that Marcion held that Jesus was Elohim, the god who created man and ultimately repented from his 'error' on the Cross. Irenaeus however systematic develops this understanding into a claim the Marcionites separated Jesus and Christ by means of the idea (found in Adv Marc 2) that 'Christ' was distinct from the Creator:
In fact Marcion's very anxiety, by means of the instances cited, to set Christ in opposition to the Creator, does rather envisage their unity [Adv Marc 2.29]
Figuring out how this idea developed is key to understand the emergence of Irenaeus's theology out of the reports of Theophilus and other early Fathers.
