http://en.wikipedia.org/wiki/Satanist
Satanism is a religious, semi-religious and/or philosophical movement whose adherents recognize Satan, either as an archetype, literal being, pre-cosmic force, or anything inbetween. Some Satanists celebrate aspects of human nature represented by the usually Christian or literary (Milton, Goethe) Satan archetype. Many Satanists do not worship a deity called Satan or any other deity. 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. However, some Satanists do have moral codes, e.g., the 9 Statements or 11 Laws of the Laveyan Satanists.
It should be noted that the depiction of so-called "Gothic Satanism" is not actually known to be practiced in the world today. This is the Satanism accused during the Inquisition, with tales of murder and baby-eating.
Many contemporary Satanists eschew traditional religious beliefs, attitudes and worship in favor of a more egotistic worldview and practices such as magick. Groups or individuals described in some sense or another as Satanic can largely, though incomprehensively, be described as belonging to one of two unofficial sub-groupings: Philosophical Satanism or Religious Satanism.