I definitely think some of it is the enemy trying to tuse what they do that is bad with the name of Satan so it misleads people. I have been a huge metal fan for a while and while some is probably what I said above I truly believe some of the remaining holders of secret knowledge went into music (especially metal) to express it, whether they are artists themselves or only help produce the music. Tool for example in concert has used occult symbols which actually give more power to the music. Most fans don't even know this.
