Now, Manicheans are not exactly a heresy, but they appear in the Confessions, and they’re very important. So since we’re doing doctrinal ideas, Manicheanism is a teaching about good and evil that can be applied to other religions besides Christianity. Manicheanism basically says that good and evil have a real existence. There is a war in the universe between a good god and an evil one. And this may be applied outside of Christianity or within Christianity.
And within Christianity, the evil god is the devil, or according to the Manicheans of this period that Augustine for a while joined, the god of the Old Testament. Jehovah is the evil god, and the god of the New Testament, the Christian god, is the good one. Jehovah is the one who smites a lot of people. Jehovah is the creator god, because the Manicheans believed that matter is evil and is the source of evil. Spirit is good. The Christian god created spirit. Human beings are imprisoned in the body, and they have to figure out a way to liberate themselves from the dominion of the evil god. Vegetarianism, for a start, avoiding flesh.
But salvation means casting off the flesh. How is this different from Christianity? And doesn’t this sound to you like regular old Christianity, mistrust of the flesh? The devil is identified with sexual desire or physicality, generally. Manicheanism is very useful as an explanation of evil. And this may not be something that keeps you up at night, but it will at some point, intermittently.