No, atheists can be assholes too, but being one does not make you any better or worse a person IMO.
Atheists don't kill in the name of God, which gives them one less reason to kill. Pretty much the biggest reason in the history of mankind to kill actually.
People are always going to kill each other over jealousy, rage, mental instability, etc. no matter what religion they are. We don't need to add to the death toll because "the invisible man that I believe in tells me different things than the invisible man that you believe in"