Are there any Christian Satanists? Cause, to worship Satan, you have to be Christian, Jewish or Muslim, right?
The way I see it, you could be Satanist in two basic ways. The first way is to just worship Satan without believing in "God". But in that case, what makes Satan any different from a universal deity like "God" or "Allah"? Not much. Satan still has to take full responsibility for creation, for morals, good people as well as bad people, etc. Doesn't make him much different than any other god.
The second way is if you worship Satan to actively reject another god. So you believe in the rule of death and pain and infinite night. You believe that Satan is gathering his powers and will conquer "God" one day. You believe that he was right to challenge "God" and that, though he lost the battle, he will win the war. Oh yeah, that's exciting! But that means that you believe in the current supremacy of another god.
So, in the first case, you don't really believe in anything remarkable, and you don't need to wear black nor drink blood, because Satan also created flowers and marshmallows.
But in the second case, you're accepting Abrahamic theology, which says that "God" is currently supreme. You're not accepting that this god will be supreme forever, but you are accepting this god currently.
Which makes you either a Muslim, a Jewish, or a Christian Satanist.