Mhh Satanism was never about believing in Satan, not inside the church of Satan, nor in the temple of Satan.
Being Satanist means to actively disbelieve in any god at all, it's about science instead of believe, about equality instead of hierarchy...
And if you wanna know why it's called Satanism then, I can explain it very easy - according to the Bible, anyone not following "God's" words, is a Satan. It means to not obey religious believes.
So we don't believe in any god = we are Satan to them, so that's why. The TST is more for science, while the church of Satan is more for elitism. That simple.
Before people talk about Satanism, they shall possibly read the satanic Bible by LaVay to find out by themselves, that it's clearly not about believing in Satan or being evil, not about grave digging or something, they are totally normal people fighting religious missuse. Actually something that is more modern than most people's mind out there.
They even see humans equal as an animal to other animals, while religious groups often see the human as superior to any animal, which slowly turns by vegetarians and educated youth, while the satanic bible referred to that 40 years ago, face it, they are just stages higher in their mindset as most. Fact which can be approved by reading before blindly judging...