Without a divine lawgiver, there can be no objective right and wrong, only our culturally and personally relative, subjective judgments. This means that it is impossible to condemn war, oppression, or crime as evil. Nor can one praise brotherhood, equality, and love as good. For in a universe without God, good and evil do not exist—there is only the bare valueless fact of existence, and there is no one to say that you are right and I am wrong.
No atheist or agnostic really lives consistently with his worldview. In some way he affirms meaning, value, or purpose without an adequate basis.