Atheists who announce "I'm good without god"

[polymath257]

The nature of morality is the rules of behavior to produce societies that promote human well being. Which rules work best are partly determined by our genetics.

Who's well being?    You just seem to be trying to determine what is moral, and not making a case for what morality is.   You are making statements, and not giving reason or evidence for your position.  Morality is the principles concerning right and wrong behavior or what one ought to do.  How do you get there from evolution?

No, morality is the rules we adopt to promote human well being. Right and wrong are words we use to drive the point home, nothing more. Those rules come from our evolutionary past: they are the rule that promote well being *in humans*. Bonobos or chimps or dogs may well have very different rules based on *their* evolutionary past.
I consider most philosophical discussion concerning 'what something is' to be seriously flawed. They tend to assume an outdated concept of ontology. It is much better to determine the epistemology since that has practical aspects.