Well, the holy book begins "Our Father, who wert in Heaven" (Anton leVey's version). Frankly, I thought it hilarious. Most 'Satanists' are just rebellious types with a grudge against Christianity. If you want to dig into it, read A. Crowley -``Do what thou wilt shall be the whole of the Law.'' OTOH, if you want to make feathers fly, tell a theist that Satanism is a Christian sect.
My book, a setting for fantasy role playing games based on Bantu mythology: Ubantu