I can completely understand how some people become agnostics, atheists, etc. I give them a break.
But devil worship? Just plain stupid, man! Look at it this way... proof of a devil is proof of a God, but proof of a God is not proof of a devil. So the logical conclusion of that is that if you believe in the devil you must also believe in God.
Where is this leading? It's leading to my blanket statement that for someone to worship the devil, they have to be about the stupidest person alive!
Worshiping Satan is not so much choosing Satan but is more rejecting God. It's an extremely immature type of temper tantrum.