Every time I have tried to study Satanists with even the most open mind, I run away at a certain point because it freaks the hell out of me. Most mainstream information of Anton LeVay, for instance, paints him as an atheist who enjoys dressing up at parties to scare Christians, but this barely scratches the surface. It scares the hell out of me that they can be so calm and cool about praising Satan and practicing occult mumbo jumbo as if they believe it was all real. It's like the Addams Family, except they are laughing at us, not the other way around.
Even if it's all fake, I still think these people are so fundamentally demented to believe what they say. There is no way I would ever give them a free pass and rule out the possibility that something awful is happening hidden behind closed doors.