Well, I am running for high priest -- or at least regular priest, if I don't find a new dealer -- of Athe, so obviously I can't be wrong
But now seriously, while Manicheanism is indeed a good illustration of such dualism, there were a TON of dualist gnostic sects in Christianity too, which probably reflect his position a lot better. The Marcionism that Tassman mentioned is probably closer to the mark, although Gaetan seems to be a bit more extreme than Marcion was ever supposed to be. I mean, Marcion was after all a disciple of Paul, and Paul never went to such extremes as to flat out consider Judaism a work of Satan.
But yeah, you can find all sorts of extremes of dualism in gnostic Xianity. E.g., going all the way to, for example, the Cainites, which would read like a joke sect by some modern Vampire The Masquerade players reciting from the Book Of Nod, if it weren't actually an ancient sect and described by Irenaeus.