They weren't insane. These were well-educated men with a sincere belief that they were doing God's work.
it's just an analogy, I meant that people can still do harmful things without believing they are doing a bad thing, not only insane people but also people like those.
for me I consider those people to be insane as well, not your typical insanity, but some people can be extremely ignorant or delusional that they can commit acts according to twisted beliefs, be it racism, pure hatred, twisted form of religion, grandiose delusions etc.
it doesn't make what I believe as a Muslim or the Quran as it is an evil thing, you think you would have ONLY gotten 19 people out of 1.5 billion believers to do 9/11 if it really stemmed from our religion as it is?
is Christianity evil because it was the driving force behind the crusades?