Atheistic morality is a contradiction in terms.  Morality addresses what ought to be, and atheism allows the existence only of what is.  Atheists have come up with various formulations to defend the notion of atheistic morality, most based on what will benefit the survival of the species.  This leaves the atheist in a difficult position, however, for the atheist believes in materialism- that there are no such things as spiritual realities, and only the material is real.  If that is the case, then the atheist can only define morality in terms of what is natural, and can only determine what is natural by observation.  Nobody talks about how a bird ought to build a nest.  They only talk about how it does build the nest.  Therefore, the atheist must determine morality simply by observing what people actually do, and defining morality in those terms.

In the atheist view, morality can only be natural, since there isn’t anything other than nature.  If atheists believe that morality is natural, then people’s actual, observed behavior defines morality.  There can be no standard to judge people’s behavior except what one actually sees, at least in the majority.  Are the majority of people racist?  Then racism must be moral.  Are the majority dishonest?  Then dishonesty is moral.  Is self-sacrifice, honesty, humility and altruism a minority position?  Then those positions must be unnatural, on the order of a bird that doesn’t know how to build a nest, and therefore immoral.

No atheist therefore has any ground to speak of how anyone ought to be.  They can only, at best, observe how someone is.  All disagreements about morality are therefore disagreements about what renders the species more fit for survival, and such disagreements, as has always been the case, can only be settled by bloodshed.  In that case the Nazis were correct- believing themselves to be the superior race with the superior morality, they set out to prove it, to subjugate or destroy all other races.  In the atheist worldview, the only thing that rendered the Nazis immoral was the fact that they failed.  If they had succeeded, then genocide would be proven good and right.