Here is some information for the people new to Satanism.
Our use of the terms "Satanism" and "Satanic:"
We define a religion according to the beliefs of the actual followers.
So, for example, we define any religious organization or individual as "Christian" if the faith group or person sincerely, thoughtfully, devoutly, prayerfully considers themselves to be Christian. This includes Fundamentalists, Evangelicals, Baptists, Charismatics, Pentecostals, mainline Christians, liberal Christians, Mormons, Unificationists, United Church members, Roman Catholics, Gnostic Christians and even Jewish Christians from the 1st Century CE. We list all as Christian even though they follow very different beliefs and practices.
So too, we regard as Satanists any group or individual who sincerely and thoughtfully considers themselves to be Satanic. This includes religious Satanists -- who are typically adults, -- and Satanic "dabblers" who are often teens.
The following are recommended terms and descriptions of two essentially unrelated beliefs and activities that recognize Satan in their belief system:
This religion recognizes Satan, generally as a life principle. Followers are usually serious adults, although a few are mature teenagers. Of the many main traditions which exist, the Church of Satan is by far the largest. Other Satanic groups currently exist and have existed in the recent past. Many are short-lived; their web sites often come and go within a few months. According to Statistic Canada, the 1991 census found only 335 Canadians who identified themselves as Satanists. This would imply that there may be on the order of 3,500 Satanists in the U.S. The actual number is probably significantly larger. A US Department of the Army pamphlet #165-13 estimated that there were 10 to 20 thousand members of the Church of Satan in the US during the late 1970's. 1,2 Accurate data for this movement is impossible to estimate, since the largest group (the Church of Satan) does not release its membership totals.
It is important to realize that the Satan that they recognize has few if any points of similarity with the historical Muslim or Christian concept of Satan. The Satanists' concept of Satan is pre-Christian, and derived from the Pagan image of power, virility, sexuality and sensuality. To almost religious Satanists, Satan is a force of nature, not a living quasi-deity. Their Satan has nothing to do with Hell, demons, pitchforks, sadistic torture, buying people's souls, demonic possession, performing miracles, human sacrifices, cannibalism, and profoundly evil deeds.
(taken from satanist-online)