Yaknow, this is part of the problem. 

It's fine to tell people not to murder, cheat, and rob other people because that's not cool, but frequently, when someone complains about morality, it's a case of them wanting to tell someone else how to worship the Almighty, what they can or can't do in their bedroom (beyond the whole murder, cheat, and rob thing), who they can love (there are people who would limit this to an opposite-gender member of your own race who believes in the God they approve off), who they can sleep with, and whether or not they can avoid having children (not just Abortion, but Birth Control as well). 

All the various mass murderers had one thing in common -- an utter disdain for people around them. They really aren't much different from the 'fine folks' who march under Nazi and Confed flags, the Militant Vegans screaming about drinking cows milk, or the asshat that cuts you off in traffic. They really only vary by how far they are willing to go with their disdain.