Which just exemplifies they're stupidity in the first place.
Well, no, not anymore than believing in God and Satan, or God alone.
In fact, I think there is more of a reason to believe in Satan than God if we were to overlook the fact that neither have any real evidence pointing towards their existence.
Believing in God and Satan is... stupid. I can't really say ignorant. Just believing in one or the other I would say is a bit more stupid.
IN MY OPINION...
*cough*
klo
*cough*