If there is no God, then there is no way to say any one action is “moral” and another “immoral” but only “I like this.” If that is the case, who gets the right to put their subjective, arbitrary moral feelings into law? You may say “the majority has the right to make the law,” but do you mean that then the majority has the right to vote to exterminate a minority? If you say “No, that is wrong,” then you are back to square one. “Who sez” that the majority has a moral obligation not to kill the minority?