Actually, theres two separate parts of satanism
There is satanism, which got its name during the dark ages, its the practice of gathering worldy knowledge and being humanistic(i. e. Renniasance), as well as having a general theory of good/evil balance, then there is satanic worship, which takes the above ideas and adds goat sacrifice and such to the mix.
Sadly, people get them confused easily, which leads to confusion.
In conclusion
Satanism: There is balance, and you should try to learn and be happy
Satanic Worship: Sacrificing goats, dancing naked in the woods like a fairy and drinking blood
True there are Satanic cults out there that blantantly worship the Devil, but what I am talking about is modern Satanism. I was once involved in the Church of Satan - I know how they work.