I think everybody has free will to do whatever they want.... That's God's given right. I don't think you can blame it on religions or other people if you did something seriously wrong. And, besides that, psychopathic people are going to kill people no matter what if they made up their mind about it. Look at Pol Pot from Cambodia.... That man has no religions, and he is one of the most hated man, probably the most hated person, in Southeast Asia.... i don't think any major religions condone that type of behavior.
Sorry, but evolution gave me intelligence and intelligence gave me free will. No superstition needed.
And hey, do you really want to start naming people through history that have done atrocious things? Because I can bet a lot more of them were religious than not.