From http://religion-cults.com/Occult/Satanism/Satanism.htm

"Satanism", is the worship and imitation of the biblical Satan or Lucifer. It is the antithesis of Judaism and Christianity. Satan is referred as the brother of Christ, the one who was cast out of heaven, and whom the Satanists worship. Condemned by the Bible and the Church, see The Occult

   - The "emblem", is a pentagram, like the one of witchcraft, but inverted, with the face of Satan on it. It is not witchcraft, although in practice the edges of Satanism and Witchcraft are blurred.

   - The "credo", is summed up in "do what thou wilt shall be the whole of the Law", coined by Crowley in "The Book of the Law".

1- Those who believe that Satan exists and is a powerful force... with animals and children sacrificed to worship him and get his favors, and the Black Mass as the main rite.

   2- Those who believe that Satan does not exist, but it is merely the symbol or personification of fleshy human desires and appetites... and they try to imitate it, with all kind of sins, pleasures and selfishness, lying, steeling, killing...

There are not many Satanists, may be less than 10,000 in the world!... only curiosity and sensationalism pays them much attention, and the actual satanic activity has been greatly exaggerated.

   But there are several categories:

   1- Group secretive Satanists: They believe that Satan really exists.

   - The "Traditional", hate Christianity, celebrate the Black Mass, in the cup they drink blood of a sacrificial animal or human, to mimic the Mass.

   - "Nontraditional", from Neo-Platonism, Eastern Mysticism, and Islam, or off-shots of the Kabbalah, Theosophy, Rosicrucianism, Freemasonry... the "blood" they drink is not necessarily a parody of the Catholic Mass, but to partake of the "fire energy" that blood provides.

   2- Public Church Satanists:

   No secret, hold worship services open to the public, based mostly on the writings of Anton LaVey's "Satanic Bible", and they believe that Satan is a symbolic force: The Church of Satan of LaVey, Temple of Set. The Church of Thelema of Crowley, the Order of the Golden Down, and derivations of the Ordo Templi Orientis (OTO), may also be included in this category.

   3- Youth Gang Satanists, that may or may not believe that Satan exists: "Dabblers" who see Satanism as a symbol of rebellion against any authority. For most, interest in Satanism is a passing fad influenced by drugs, sex, and rock-and-roll, but with serious consequences, like in the spectacular case of Charles Mason, or Andrew Newell who stabbed his mate to death, or Peter McKenzie who sexually abused 13 children.

   4- Individual Satanists, often disturbed individuals, neurotic or psychotic, like most Satanists!.

"Do what you will" is the general principle. What is "bad" in the Bible becomes "good"; sin!, and Satan will be with you!... they call it "freedom of choice"; they believe to get powers to perform magic by doing evil acts.

- At the low level, they burn crosses, spray Satanic graffiti, dig up graves...

- A higher level is by burning churches, doing all kind of sexual aberrations, steeling, drugs...

- Children sexual abuse is a higher level... and, of course, the ultimate evil is "killing", children or adults, the greatest release of magical energy.

This is the ultimate rite for a real Satanist to obtain magic powers: A blasphemous Mass, where the altar is a nude woman, and the vagina is the tabernacle. If possible, a real Host stolen from a Catholic Church is placed in the vagina in the midst of reciting distorted psalms with hot music and all kind of obscenities, coursing Jesus and honoring Satan. The fake priest ends up having real sex, with the Host still in the vagina.

   ... If a baby can be slaughtered during the ritual, they will drink his blood and eat his flesh, to mimic the most the Eucharist...

.    .. Ideally, a Black Mass is to be celebrated by a "real heretic Priest", that, even in sin, can celebrate Mass effectively.

   - The prayers end with the strongest expression of Satanism: "Shemhaforash", the word pronounced by God when he created the World, and, while spitting on a cross or stepping on it, they all cry out "Hail, Satan".

.    .. And, of course, it may end up with a sexual orgy with all kind of abominations and abuses, under the influence of drugs.