I don't doubt it but those don't typically go around committing mass murder.

As far as the 'people are willing to kill and die for them' bit goes, that's a pretty good definition of insanity to me. After all if an idea was placed in your head and you then go out and use that idea as justification for murdering innocents that you have no personal grievance against (the one universal that most people seem to agree on is a bad thing) then there is something not entirely right in your head.