I could continue to go down chapter by chapter in Book One but I presume you can read. The argument is clearly the Marcionites argued from the Jewish scriptures that there were two gods in the Jewish pantheon. What is so difficult to understand about this? What is the fucking obstacle to taking the next step and identifying the two powers group with Marcionism? Segal just about did it. Pity he didn't spend enough time familiarizing himself with the sect a little better. At least you have that opportunity given that you are still alive and he did.[Marcion] presumed that there ought to be another god, after the analogy of the good tree producing its good fruit. [Adv Marc 1.2]
But some one may contend that two great Supremes may exist, distinct and separate in their own departments; and may even adduce, as an example, the kingdoms of the world, which, though they are so many in number, are yet supreme in their several regions. Such a man will suppose that human circumstances are always comparable with divine ones. Now, if this mode of reasoning be at all tolerable, what is to prevent our introducing, I will not say a third god or a fourth, but as many as there are kings of the earth? Now it is God that is in question, whose main property it is to admit of no comparison with Himself. Nature itself, therefore, if not an Isaiah, or rather God speaking by Isaiah, will deprecatingly ask, "To whom will ye liken me? " Human circumstances may perhaps be compared with divine ones, but they may not be with God. God is one thing, and what belongs to God is another thing. Once more: you who apply the example of a king, as a great supreme, take care that you can use it properly. For although a king is supreme on his throne next to God, he is still inferior to God; and when he is compared with God, he will be dislodged from that great supremacy which is transferred to God. Now, this being the case, how will you employ in a comparison with God an object as your example, which fails in all the purposes which belong to a comparison? Why, when supreme power among kings cannot evidently be multifarious, but only unique and singular, is an exception made in the case of Him (of all others) who is King of kings, and (from the exceeding greatness of His power, and the subjection of all other ranks to Him) the very summit, as it were, of dominion? But even in the case of rulers of that other form of government, where they one by one preside in a union of authority, if with their petty prerogatives of royalty, so to say, they be brought on all points59 into such a comparison with one another as shall make it clear which of them is superior in the essential features and powers of royalty, it must needs follow that the supreme majesty will redound to one alone,--all the others being gradually, by the issue of the comparison, removed and excluded from the supreme authority. Thus, although, when spread out in several hands, supreme authority seems to be multifarious, yet in its own powers, nature, and condition, it is unique. It follows, then, that if two gods are compared, as two kings and two supreme authorities, the concentration of authority must necessarily, according to the meaning of the comparison, be conceded to one of the two; because it is clear from his own superiority that he is the supreme, his rival being now vanquished, and proved to be not the greater, however great. Now, from this failure of his rival, the other is unique in power, possessing a certain solitude, as it were, in his singular pre-eminence. The inevitable conclusion at which we arrive, then, on this point is this: either we must deny that God is the great Supreme, which no wise man will allow himself to do; or say that God has no one else with whom to share His power. [Adv Marc 1.4]
But on what principle did Marcion confine his supreme powers to two? I would first ask, If there be two, why not more? Because if number be compatible with the substance of Deity, the richer you make it in number the better. Valentinus was more consistent and more liberal; for he, having once imagined two deities, Bythos and Sige,62 poured forth a swarm of divine essences, a brood of no less than thirty Aeons, like the sow of Aeneas.63 [2] Now, whatever principle refuses to admit several supreme begins, the same must reject even two, for there is plurality in the very lowest number after one. After unity, number commences. So, again, the same principle which could admit two could admit more. After two, multitude begins, now that one is exceeded. In short, we feel that reason herself expressly64 forbids the belief in more gods than one, because the self-same rule lays down one God and not two, which declares that God must be a Being to which, as the great Supreme, nothing is equal; and that Being to which nothing is equal must, moreover, be unique. [3] But further, what can be the use or advantage in supposing two supreme beings, two co-ordinate65 powers? What numerical difference could there be when two equals differ not from one? For that thing which is the same in two is one. Even if there were several equals, all would be just as much one, because, as equals, they would not differ one from another. [4] So, if of two beings neither differs from the other, since both of them are on the supposition66 supreme, both being gods, neither of them is more excellent than the other; and so, having no pre-eminence, their numerical distinction67 has no reason in it. Number, moreover, in the Deity ought to be consistent with the highest reason, or else His worship would be brought into doubt. For consider68 now, if, when I saw two Gods before me (who, being both Supreme Beings, were equal to each other), I were to worship them both, what should I be doing? [5] I should be much afraid that the abundance of my homage would be deemed superstition rather than piety. Because, as both of them are so equal and are both included in either of the two, I might serve them both acceptably in only one; and by this very means I should attest their equality and unity, provided that I worshipped them mutually the one in the other, because in the one both are present to me. If I were to worship one of the two, I should be equally conscious of seeming to pour contempt on the uselessness of a numerical distinction, which was superfluous, because it indicated no difference; in other words, I should think it the safer course to worship neither of these two Gods than one of them with some scruple of conscience, or both of them to none effect. [Adv Marc 1.5]
Thus far our discussion seems to imply that Marcion makes his two gods equal. For while we have been maintaining that God ought to be believed as the one only great Supreme Being, excluding from Him every possibility69 of equality, we have treated of these topics on the assumption of two equal Gods; but nevertheless, by teaching that no equals can exist according to the law70 of the Supreme Being, we have sufficiently affirmed the impossibility that two equals should exist. For the rest, however,71 we know full well72 that Marcion makes his gods unequal: one judicial, harsh, mighty in war; the other mild, placid, and simply73 good and excellent. [2] Let us with similar care consider also this aspect of the question, whether diversity (in the Godhead) can at any rate contain two, since equality therein failed to do so. Here again the same rule about the great Supreme will protect us, inasmuch as it settles74 the entire condition of the Godhead. Now, challenging, and in a certain sense arresting75 the meaning of our adversary, who does not deny that the Creator is God, I most fairly object76 against him that he has no room for any diversity in his gods, because, having once confessed that they are on a par,77 he cannot now pronounce them different; not indeed that human beings may not be very different under the same designation, be because the Divine Being can be neither said nor believed to be God, except as the great Supreme. [3] Since, therefore, he is obliged to acknowledge that the God whom he does not deny is the great Supreme, it is inadmissible that he should predicate of the Supreme Being such a diminution as should subject Him to another Supreme Being. For He ceases (to be Supreme), if He becomes subject to any. Besides, it is not the characteristic of God to cease from any attribute78 of His divinity--say, from His supremacy. For at this rate the supremacy would be endangered even in Marcion's more powerful god, if it were capable of depreciation in the Creator. [4] When, therefore, two gods are pronounced to be two great Supremes, it must needs follow that neither of them is greater or less than the other, neither of them loftier or lowlier than the other. If you deny79 him to be God whom you call inferior, you deny80 the supremacy of this inferior being. But when you confessed both gods to be divine, you confessed then both to be supreme. Nothing will you be able to take away from either of them; nothing will you be able to add. By allowing their divinity, you have denied their diversity. [Adv Marc 1.6]
But this argument you will try to shake with an objection from the name of God, by alleging that that name is a vague81 one, and applied to other beings also; as it is written, "God standeth in the congregation of the mighty;82 He judgeth among the gods." And again, "I have said, Ye are gods."83 As therefore the attribute of supremacy would be inappropriate to these, although they are called gods, so is it to the Creator. [2] This is a foolish objection; and my answer to it is, that its author fails to consider that quite as strong an objection might be urged against the (superior) god of Marcion: he too is called god, but is not on that account proved to be divine, as neither are angels nor men, the Creator's handwork. If an identity of names affords a presumption in support of equality of condition, how often do worthless menials strut insolently in the names of kings--your Alexanders, Caesars, and Pompeys!84 This fact, however, does not detract from the real attributes of the royal persons, Nay more, the very idols of the Gentiles are called gods. Yet not one of them is divine because he is called a god. [3] It is not, therefore, for the name of god, for its sound or its written form, that I am claiming the supremacy in the Creator, but for the essence85 to which the name belongs; and when I find that essence alone is unbegotten and unmade--alone eternal, and the maker of all things--it is not to its name, but its state, not to its designation, but its condition, that I ascribe and appropriate the attribute of the supremacy. [4] And so, because the essence to which I ascribe it has come86 to be called god, you suppose that I ascribe it to the name, because I must needs use a name to express the essence, of which indeed that Being consists who is called God, and who is accounted the great Supreme because of His essence, not from His name. In short, Marcion himself, when he imputes this character to his god, imputes it to the nature,87 not to the word. [5] That supremacy, then, which we ascribe to God in consideration of His essence, and not because of His name, ought, as we maintain, to be equal88 in both the beings who consist of that substance for which the name of God is given; because, in as far as they are called gods (i.e. supreme beings, on the strength, of course, of their unbegotten and eternal, and therefore great and supreme essence), in so far the attribute of being the great Supreme cannot be regarded as less or worse in one than in another great Supreme. [6] If the happiness, and sublimity, and perfection89 of the Supreme Being shall hold good of Marcion's god, it will equally so of ours; and if not of ours, it will equally not hold of Marcion's. Therefore two supreme beings will be neither equal nor unequal: not equal, because the principle which we have just expounded, that the Surpeme Being admits of no comparison with Himself, forbids it; not unequal, because another principle meets us respecting the Supreme Being, that He is capable of no diminution.
[7] So, Marcion, you are caught90 in the midst of your own Pontic tide. The waves of truth overwhelm you on every side. You can neither set up equal gods nor unequal ones. For there are not two; so far as the question of number is properly concerned. Although the whole matter of the two gods is at issue, we have yet confined our discussion to certain bounds, within which we shall now have to contend about separate peculiarities. [Adv Marc 1.7] ...
I am certain that the late second century references to the Marcion and the Marcionites 'crime' for venerating another god besides the cosmocrator closely parallel the two powers sect (= the circle of R Ishmael). Both had before them a Samaritan edition of the Book of Exodus which makes explicit just that - viz. that there were two powers manifest at Sinai. The two don't have to be identical beyond that detail. There may at one time have been a number of Jewish sects who differed in terms of the application of the same Torah. But the circle of R Ishmael and the Marcionites retained the use of the 'un-monarchian' (?) Samaritan edition of Exodus (i.e. a narrative which denied any quarter for monotheism).