But Nietzsche's geneology is too crudely egoistic, for my taste. He assumes the worst motive for everyone (will to power).

Who made the parody? The author of Mark and the Gnostics. To what end? To write great literature, to help Jews understand how they should evolve after the disastrous Jewish-Roman wars.

Alternatively, there's a conspiracy theory that the Romans were behind the rise of early Christianity, that Roman elites spiritualized Judaism to tame it.