Religion?

Originally Posted by wolf

I thought that the true irony of Satanism is that in order to be a Satanist you had to believe in the Christian God-Concept.

Nope.
Think of it as an anti-Buddhism. Instead of ridding yourself of the Beast, emotions and hedonism you become one/one with them... there is no faith, no real dogma. It is very much based in the teachings of Nietzsche.
The Christianity part is just imagery to show what it is against & a very convenient way to weed-out undesirables who think they may want to be part of the church.