Theistic satanists take the blatantly untrue accusations against largely innocent people of centuries' past and believe it to be some sort of truth. There was no sabbat, no dark meetings in the forest...none of it was true. It was nonsense created by Christians and thrust upon unfortunate people who had to accept the false narratives under duress of torture or were convinced of the untruth due to having a form of mental illness. The problem? It was all made up, but the poor men and women paid the price for it.
It's the worship of black propaganda by Churchmen. I can't think anything more false than that.
Atheist satanists are merely jumping on the rebellion Satanism represents.