When questioned about my lack of belief in gods and demons, I am often asked how I know right from wrong. This is an clear challenge of my atheism as a preclusion to my ability to lead a moral life. The argument is that our most noble codes of conduct must have been dictated by god, more specifically to Christians, the god of the bible (yes, I purposely write such names with lowercase initials, albeit grammatically incorrect), who in his omniscience, provided humanity with the perfect moral law.
Whenever I encounter the proposition that I cannot be moral without Yaweh and his commandments; I wearily attempt to discuss my limited understanding of how evolutionary processes coded morality into our genetic expressions of behaviour. This, despite my best efforts, fails to move people in my direction. I admit that I have to improve this part of my discourse.
Lately, instead of sharing evolution with my opposition, I have taken on the challenge of presenting another point of contention, one holding that religious convictions are perfectly immoral when they are observed for fear of damnation in the hereafter.
Good moral people do good things because they know it to be good, not for the expectation of recompense. As a humanist, I respect people for two reasons: it is the correct course of action, and, at the end of the day, it just feels nice to do it.