"If there is no God, we don't have to follow His rules on sex, selfishness, pride, ambition, greed, servanthood. We can put ourselves and our desires first. We can go into the world and sneak, lie, cheat and do whatever it takes to get ahead. And have nothing and noone to answer for or too."
Meanwhile we non-fundie Christians/Muslims/Hindus etc, Buddhists, Wiccans, Agnostics, Humanists/Atheists behave towards each other in a civilised way, via the Pragmatic Social Imperative (if you're nice to others, other people will be nice to you, and all that jazz. Communal acts of kindness helps out the community, and thus humanity benefits as a whole).
Buddhists refer to it as Karma. Acts of goodness results in more good things happening to you. Evil acts result in bad things happening (Example: Gandhi becomes a revered figure in India. Saddam Insane does a merry dance on the end of a rope).
Treat others as you would want them to treat you. Commit acts of gratuitous kindness. Be good for goodness' sake.
I wouldn't like to be killed/harmed, nor would I want my property stolen/damaged, so why should I do the same to others?
No 'God' required.
I love the smell of destroyed arguments in the morning. Smells like... victory.