satanist

noun

1. the worship of Satan or the powers of evil.
2. a travesty of Christian rites in which Satan is worshiped.
3. diabolical or satanic disposition, behavior, or activity.

noun

1. the worship of Satan
2. a form of such worship which includes blasphemous or obscene parodies of Christian prayers, etc
3. a satanic disposition or satanic practices

n.1550s, from Satan + -ist. Ppplied by their enemies to Protestant sects. Meaning “Satan-worshipper” is from 1896. n.1560s, “satanic disposition,” from Satan + -ism. Applied 1820s-30s to the poetry of Byron, etc. Meaning “worship of Satan” dates from 1895, with reference to France, where it was said to be active at that time.