Perhaps you should visit the Church of Satan website. I don't have the link, but if you use Yahoo Search, you will find it. Their website does have a lot of information about satanism and the reasons why they worship Satan and not God.
Personally, I do not believe in the devil, but since the Constitution grants you the Right to Religious Cult, I have told you where to find the information you want.
You can buy the Satanic Bible at any bookstore in the world, so go buy this and actually read it. We need more people in this world worship ping the dark master.
It depends on weather you mean people who actually worship and believe in a supernatural being called Satan, or LaVey satanism, the church of Satan as founded by Anton LaVey. I don't know if there are many actual satanists, and I don't know anything about them.
LaVey satanist don't actually believe in an actual being named Satan, and they don't believe in god either. They use the character of Satan as a metaphor to represent the things they feel are important. They are an atheistic religion that focuses on living life to feel good, and fulfill yourself by doing things that bring you pleasure. Their black masses are designed to mock mainstream religion, which they see as limiting and oppressive.
There's a lot of information about LaVey satanists on the net, you have only to look.
Satanists would tell you it's the "worship of the self". Most people who identify themselves as Satanists are the "LaVeyian" variety. Anton LaVey was a liar, fraud, bankrupt wife beating pimp. BTW, one idiot actually had the nerve to say "Everyone beat their wife in the fifties" when informed of this(even though he beat Diane from the 60's into the 80's). And no, not everyone did, and it was still wrong.
This shows that rather than standing on their own two feet, Satanists slavishly make excuses for their cult figure, not unlike they way Scientologists do foe L. Ron Hubbard.
LaVey was approached by Avon books to wrote a book on witchcraft to cash in on the occult craze of the 1960's. He cobbled together "The Satanic Bible" from a forgotten right-wing political tract (Where of the material from the Book of Satan comes from), Ayn Rand's Atlas Shrugged, and the superstitious occult material of John Dee.
LaVey never really seemed to know what Satanism was himself. Some of his writings seemed atheistic, at other times he called Satan "the dark side of nature" and often refers to Satan as a personification. One thing is for certain, the Satanic Bible gives specific instructions on timing, tools to be used, specific rituals for sex spells, revenge spells, etc (The Book of Belial)., and it seemed he expected results.
Eventually, people realized the spells didn't work, and so began the whole "Well, it's really a philosophy" excuse. In the 1980's, when LaVey was living in poverty he then claimed he was shunning consumer materialism ( a complete role reversal from "Indulgence instead of abstinence!") ala Pee Wee Herman's "I meant to do that!"
LaVey claimed that nuts were given "the bum's rush" when trying to join the Church of Satan, but clearly nut was in the eye of the beholder. LaVey has admited to holding a "Cannibal feast" of a human leg in at least 3 books. The Satanic Bible &Satanic Rituals certainly describe many things most normal people would consider pychotic such as Nude girl is used as an altar (Satanic Bible, Satanic Rituals)A human skull is used in Die Elektrischen Vorspiele ritual (Satanic Rituals, p. 109)Human leg bone or arm bone is used in Homage to Tchort ritual (p.137)
Woman dressed as nun urinates before group into a bedpan in the Black Mass ritual (p.43) Urine is then sprinkled like holy water (p.44)Man climbs into coffin with nude woman (or nude man if he is gay) in Le Epais ritual (p.59).
As a "philosophy", Satanism could be boiled down to hedonism, which was hardly a new idea in the 1960's. Oddly enough, most Satanists don't fit the bill as swingers. Some seem to lead fairly uneventful lives. Here's an example:
"I've been forced to give up coffee - the acid was responsible for a minor ulcer and I can no longer take any chances with my health. This was my solitary vice - now it is gone. I do not drink, do not smoke, do not use recreational drugs and have nothing remotely resembling a sex life!"
--"Lord" Egan of "The First Church of Satan"
Wow! What a swinger! So then the picture begins to develop that Satanism is not so much a philosophy of life as it is a fantasy; a means to escape a life not worth living.
What is a good sourse of info on Satanism?
