Why is that?
You see, many of the Church Fathers - Irenaeus and Tertullian in particular - make it seem as if the Marcionites 'hated' the Jewish god. Of course scholars of early Christianity in their erudition necessarily suppose that the Jews, Samaritans and 'orthodox' Christians were strict monotheists. This even though Christians had a 'Father' and 'Son' god.
But what is even more unusual is the repeated manner in which Marcionites 'go to the well' with respect to the story of the Exodus. Yes, to be certain there is a 'negative' aspect to their interest. They repeatedly note that the Jewish god (or perhaps 'the god of Moses') encourages the Israelites to steal the gold of the Egyptians. Yet this criticism reverberates in the rabbinic sources too. Another significant reference is found in Tertullian's Against Marcion where they are recorded as declare "one work is sufficient for our god ; he has delivered man by his supreme and most excellent goodness, which is preferable to [the creation of] all the locusts."
What isn't generally noted here is that this too is an Exodus reference. In other words, the point seems to be that Moses's god created locusts against the Egyptians while the 'Christian god' redeems his people. Of course the assumption again is that (a) 'the Jews' has only one god and (b) that the Marcionites believed 'the Christians' had a separate god. But I am not so sure about that.
Let's start with the fact that the Exodus narrative features both 'destructive' (the locusts) and 'redemptive' (the crossing of the Sea) miracles. Did all Jews originally believe that the same god both 'punished' and 'saved' in the Exodus narrative? Of course not. Philo for instance represents an extremely early Jewish tradition that saw two powers in heaven - one merciful and the other just. That Jews of this sort existed outside of Alexandria is demonstrated in the 'two powers' literature which survives in rabbinic sources.
Did Philo believe that the 'just' power who made the locusts was the same as the 'good' power who redeemed Israel? No certainly not. As we see with a number of references from Irenaeus and subsequent Church Fathers the Marcionites held beliefs very closely aligned with Philo. As such isn't it likely that what the Marcionites are saying is that Moses had access to one power, 'the just god,' who created the locusts but that Jesus manifested himself as the 'other god' - i.e. that of 'goodness' - who 'redeemed' Israel?
Why is it so 'obvious' that Marcion repeatedly referenced the Exodus because he 'hated' the Jews and 'hated' their god? It doesn't make sense. Nor does it make sense that he would have 'retained' references to the Jewish scriptures in his 'New Testament' if this was stated agenda. Indeed if we go through another of the references to Moses in Tertullian - i.e. the criticism that this power made Moses manufacture a serpentine idol (2.23) it is clear that the Marcionites were not monotheists and assume not only they but the Israelites interacted with two distinct powers (i.e. one of 'good' the other 'just').
Look again at what follows in 2.26 which begisn with the acknowledgement that the just power knew of another power besides himself:
What else could he have thought of doing, when he was unaware of the existence of any other god, and in fact was then and there swearing that besides himself there is no other god at all?" Do you then charge him with false or perhaps pointless swearing? But he cannot be supposed to have sworn falsely if, as you allege, he did not know there was another god: for his swearing of what he knew of was not in a true sense false swearing. Neither is his swearing that there is no other god a pointless swearing: only so would it have been pointless swearing if there had not been people who believed there were other gods—in that age worshippers of idols, in our days also heretics. So he swears by himself, so that you may believe God, at least on his own oath, that there is no other god at all. And it is you, Marcion, who have forced God to do this: for even so long ago God had foreknowledge of you. Consequently if in his promises, and in his threatenings besides, God uses an oath in dragging forth that faith which in its beginnings is hard to attain to, there is nothing unworthy of God in that which causes men to believe in God.Tertullian's answer to the original Marcionite objection that the 'just god' seems to know that there existed another god - a god of goodness - besides him, is to note the seeming inconsistency of the heretics, who also claimed it would seem that the just god was blind enough to consider himself the only god.
Yet we shouldn't take this objection seriously. For the Marcionites were likely only developing a psychological observation - namely that the just god, the so-called 'god of the Jews' was narcissistic. In the same way as narcissists are surrounded by other beings but only see themselves so too the just god. In what immediately follows this reference it is worth noting that only the one god, the 'just god' is the one Moses's wrestles with:
On that other occasion also God made himself little even in the midst of his fierce anger, when in his wrath against the people because of the consecration of the (golden) calf he demanded of his servant Moses, Let me alone, and I will wax hot in wrath and destroy them, and I will make thee into a great nation.b On this you are in the habit of insisting that Moses was a better person than his own God—deprecating, yes and even forbidding, his wrath: for he says, Thou shalt not do this: or else destroy me along with them.c Greatly to be pitied are you, as well as the Israelites, for not realizing that in the person of Moses there is a prefiguring of Christ, who intercedes with the Father, and offers his own soul for the saving of the people. But for the present it is enough that the people were granted even to Moses in his own person. Also, so that the servant might be in a position to make this re- quest of his Lord, the Lord made that request of himself. That is why he said to his servant, Let me alone and I will destroy them, so that the servant might forestall this by his prayer and his offering of himself, and so that you by this might learn how much is permitted to one who has faith, and is a prophet, in the presence of God.Moreover in yet another reference Tertullian appeals to the Marcionite belief that Jesus indeed spoke to Moses when he declares:
This name Christ Himself even then testified to be His own, when He talked with Moses ... When He therefore spake this commandment to the people, "Behold, I send my angel before thy face, to keep thee in the way, and to bring thee into the land which I have prepared for thee; attend to him, and obey his voice and do not provoke him; for he has not shunned you, since my name is upon him," He called him an angel indeed, because of the greatness of the powers which he was to exercise, and because of his prophetic office, while announcing the will of God; but Joshua also (Jesus), because it was a type of His own future name.Of course the specific argument that the Marcionite Eesu = 'Joshua' was a specifically Catholic understanding. The Marcionites clearly had another etymology for the name of their god. But it is worth noting again that the Marcionites not only believed that there were two powers in heaven in their cosmogony - i.e. a 'just god' and a 'good god' - but that the same two gods were active in the Exodus narrative, because they inherited a Jewish understanding to this effect.