An atheist may choose to deny the existence of God, while pragmatically choosing to adhere to codes that have sprung forth from the idea of God and immortality.(they are the only ones that endure)
Even Richard Dawkins, in his book "The Selfish Gene" admits that humans are born selfish as a biological reality. He proposes the need for ethical training to "learn generosity and altruism." What he can't admit is that if a human is just a biological being. . .it doesn't make natural sense for a human to act in contrary to his biological nature. . .this was Dostoevsky's point. This is what George Washington meant when he stated in his farewell address, "reason and experience both forbid us to expect that national morality can prevail in exclusion of religious principles." The "religious" view of a human is that we are not just biological in nature. . ..we are also spiritual. It is the spiritual component. .."God's image" that then makes us worthy of the "endowment" from our Creator. . .of liberty, life and the pursuit of happiness.
I don’t follow- altruistic behaviour is not limited to the human species alone. Or have I wrongly interpreted what you had meant to convey?
So basically what you’re saying is that there is no morality without god?
BTW: I’m an atheist and I consider myself very moral. I could even tell you where my morals come from and why I believe in them but they have nothing to do with a god.