Satanism is a religious and philosophical movement whose adherents worship Satan and celebrate aspects of human nature represented by the Satan archetype. Unlike many religions and philosophies, Satanism generally focuses upon the spiritual advancement of the self, rather than upon submission to a deity or a set of moral codes.

Philosophical Satanism is largely considered to have been unofficially founded by Anton Szandor LaVey with his creation of the Church of Satan, one of the first above-ground organizations to use the term. This form of Satanism views ones self as the subjective center of the universe, and the highest aspirations and virtues are those which seek the elevation and improvement of the individual Satanist over others. Philosophical Satanists generally do not recognize a theological deity or a metaphysical afterlife (though this is not to say that one MUST not), however this does not equate to a life devoid of spirituality. To the Satanist, One is Ones own God, and He disdains rationalist, secular humanistic beliefs which abhor the existence of the supernatural, only to promote a sterile life grounded in the 'real world' alone and in working towards the altruistic advancement of His fellow man while neglecting He His own gratification and amusement. Obviously, philosophically Satanic thought has had a long history before LaVey's Church, though it was the notion of Satan as the idealistic, self-seeking black sheep which inspired the title in spite of contemporary Christianity (which views him as evil because of these qualities).

Religious Satanism is often similar in outlook and attitude to Philosophical Satanism, though it is generally a prerequisite that the Satanist accept a theological and metaphysical canon involving one or more God(s) who are either Satan in the strictest, Abrahamic sense, or in some way represent or are tied to this person. Depending on the Satanists in question, this God (or Gods) may be any in a variety of deities, sometimes taken from ancient faiths; with common ones being Set of Egyptian theology, any number of ancient Mesopotamian Gods or Goddesses, sometimes Gods of Greek or Roman mythology (Mars, for instance). Others claim a largely original God, although it is usually said by those Satanists that their deity is in fact very old, perhaps from ancient pre-history and often being the first God worshipped by humans (though such claims are unverifiable at best). Others worship a stricter interpretation of Satan; that of the fallen angel featured in the Christian Bible, believing Him to be correct in his rebellion against God. All these faiths hold in common, however, with each other and with Philosophical Satanists, that man, and specifically ones self are the highest priorities. This view is often supported by the God, who is seen to encourage individuality and freedom of thought, and the quest to raise ones self up through magick and Nietzschean Will to Power. One example of this would be the Abrahamic Satan, as the Serpent in Genesis encouraging mankind to partake of the fruit of the Tree of Knowledge of Good and Evil, saying "Ye shall not surely die: For God doth know that in the day ye eat thereof, then your eyes shall be opened, and ye shall be as gods, knowing good and evil."*, with the clear implication, coinciding with the beliefs of all Satanists, that mankind should know what is better for itself than any God which would forbid knowledge and self-government. Because of the common position that their faiths are in fact very old, or the oldest, Religious Satanists sometimes refer to themselves as "Traditional Satanists" and Philosophical Satanists as "Contemporary Satanists".

- wikipedia about satanism