Apparently being a Marcionite means adhering to the teachings of the 2nd c. heretic Marcion, who saw in the Bible two different Gods: the wrathful God of the Old Testament and the happy gracious God of the New.
Definitely not killing off a people group or one’s enemies to acquire land or hold on to it.
To speak this way is not Marcionism–not even quasi, latent, or incipient Marcionism, but an articulation of a perennial theological problem of Christian doctrine: the very real presence of both continuity and discontinuity between the Testaments.
The Old Testament rhetoric of God sanctioned (or at least God tolerated) plundering of towns and taking captive children and virgin women is, I would dare to suggest, an area of profound discontinuity.
To suggest, even remotely, that this view is Marcionite in any sense of the word is only slightly less ridiculous and theologically irresponsible than the thought that I or others who think this way were born on Mars.
I don’t think the Gospel permits, condones, or supports the rhetoric of tribal violence in the Old Testament. But this does not mean I believe the Old and New Testaments give us different Gods. They give us, rather, different portrayals of God.
Different portrayals of the one God are not simply seen between the two Testaments. They are also seen within each Testament. Israel’s Scripture does not present God in one way, but various ways–depending on who is writing, when, and for what reason. Same with the New. This is what keeps theologians so busy, trying to make that diversity fit into a system of some sort.
To say that there are two Gods, one of the Old Testament and one of the New, is Marcionism. To say that the one God is portrayed in various–even conflicting–ways is simply a matter of reading the Bible in English with both eyes open.
My big concern in all this is that the charge of Marcionism simply deflects from the real theological/hermeneutical problem of divine violence by giving a false sense of having solved the problem.