Not believing in God doesn't cut you off from anything. Social ethics and standards are God-optional. Like any invisible minority, a lot of people have always been atheist, they just generally stayed quiet about it.

Even now when most people can be open about is do you seriously see any different between atheists and theists in basic morality? I don't. Atheists just leave off the 'because God said so' part

Honeslty you can just have good and bad people of different types. I think connecting the type to the goodness and badness, even if done diversely, has the opposite message to what is probably intended. It suggests that being in a beleif group a certain way makes you good and/or bad (or whatever euphemism). People will pick up on one character more than the other and see it as a stereotype.