Religion has no proof, so whats their argument when it has no validity.?

why do they all ways make fools out of them selves in astronomy and space, and say whacked out crap like " well if theirs no god whats to stop from walking out of my house right now and murdering a bunch of people" < i have heard that said a bunch of times, jesus christ these people are a bit homicidal if you ask me. is it that most of these people are only abiding to law and not running amok by killing each other because of their fear of hell?