I think the only people who worry about Satanists (for the sake of argument let's assume they're 'real' Satanists as opposed to Goths, Metallers or other Freaks who just like the imagery but no more believe or worship Satan than they do the tooth-fairy) are those, who like 'real' Satanists, have an entirely fanciful and unsupported set of beliefs.
It's a bit like people speculating whether Melchester Rovers or Oldcastle United are better teams - they're both made-up football teams from a comic, but that wouldn't stop people who've immersed themselves in the belief structure from debating their individual merits or powers as though they were real.
It is just like kids will argue about whether Snealsels or Snorlax (Pokemon) are more powerful, or whether Lickety Split, or Wind Whistler is the 'best' My Little Pony... I mean, would Darth Maul beat Luke Skywalker in a light-sabre duel? Would a P-51 Mustang beat a Supermarine Spitfire in a dogfight - oh, hang on, silly me, Mustangs and Spitfires actually exisited... but that question can never be answered as a dogfight between the two never took place...
Real.... imaginary.... DIFFERENT
Of course, anyone having proof of god OR Stan (as Satan's friends call him) can post it here, making sure they specify which god they're proving...