I don't know if Alester Crowley was really a Satanist. I heard that he really just created his own occult viewpoint by mixing various mystic philosophies of both Eastern and Western origin...such as kabbalah, Tantric, Buddhism, Hinduism, Order of the Golden Dawn, etc., and basically just put them in a blender and out came his worldview.
Add booze, heroin and sodomy to the blender and you just about got it.
He considered himself a black witch/warlock and was indeed a Satan worshipper, from my reading about him. A homosexual pedophile as well. Very nasty creature. And to have him as a mentor says volumes.