Satanist

A "Satanist" is either:

1. Theistic Satanist: One who worships the Christian devil. Although the Christian Churches taught during the Renaissance that devil worshippers were very common, most modern people believe such individuals were in fact quite rare, and that they remain so.

OR

2. Religious Satanist: One who accepts Satan as a pre-Christian life-principle worth emulating. They follow a number of religious traditions, of which the largest by far is the Church of Satan.