Where do atheists get their morality from?

[Vincenzo Vinny G.]

But genocide promotes your own survival by eradicating competition for limited resources.

So how did genocide become evil?

Have you read anything about serial strategies in game play?

It became evil when we turned to agriculture and city states, realising that if genocide were acceptable then one might well find oneself the genocidee rather than the genocider.

Optimal strategy in the longer term for ourselves and our descendants is not to kill, nor to engage in genocide, but to co-operate in managing resources and access to them on a relatively equitable basis. Genocide was the tribal religious practice celebrated still by people like W L Craig (Those poor soldiers, feeling bad about killing everyone on god's command. Have a bit of sympathy!)

So what if there is a possibility of becoming the genocidee?

All we have to do is minimize the probability of being the genocidee (haha, this word!) and maximize the probability of being the perpetrator. If you accomplish this, you have no problems. And this can certainly be accomplished. Look at Genghis Khan. Hitler. Stalin. Saddam Hussein.

Genocide is still an option that can maximize survival and reproduction possibilities in some situations.