You completely misunderstood my post.
An atheist decides what is morally right and wrong based on his/her personal views of life, what behaviors they perceive to be helpful, hurtful, etc. I certainly recognize that this leads to moral behavior in many cases. This method also works for me to some extent. But, as one who believes in God and believes that God declares what is morally right and wrong, I look to God for those answers. For example, I believe that sex out of marriage is morally wrong because God has said that sexual relations are sacred and reserved for marriage. That ends the discussion for me. No amount of philosophy, arguments, rationalizations, or studies will persuade me that sex outside of marriage is morally right. So, my argument to an atheist that sex out of marriage is morlly wrong is based on my belief in God. I find that when I use this reasoning with an atheist, they reject my argument as absurd - since they don't believe there is a God, much less that he establishes moral law.