This is an abbreviated response to an atheist friend. He believes that morality is essentially based on feelings of empathy.
-Charles Martin Cosgriff
Why, my friend, I'm glad we could find some common ground. I agree that humans are intuitive (dare I point out that the Ten Commandments are written on our hearts?), but not that morality is about empathy and compassion. For empathy and compassion are mere feelings, and we know that feelings can and do mislead. Alone, feelings may indeed inspire good moral action; proper empathy and compassion are good things. Unfortunately feelings may well lead to bad moral actions: it goes without saying that uncontrolled, instantaneous anger can cause much grief. It seems we must judge our feelings as to whether they are for well or for ill. We must look upon them rationally, acting upon them only when it is clear that they are properly driven towards good goals.
But by whose logic do we declare our feelings right or wrong, then? That's where we disagree. For Right Reason, objective morality, the Natural Law, indeed common sense, all of which are the names of one essential reality, are beyond any one person. As it is beyond us, and we must seek it in order to act within it.
That, in part, is where God comes in. For God is Right Reason, He is that objective morality. Among other ideals, He is the Natural Law. Without such a guide, even empathy and compassion may in fact lie to us: we've all heard of the Stockholm Syndrome. We may end up feeling compassion for the wrong person, cause, or reason. We must have a way to judge our feelings or they may do us a disservice rather than being a correct impetus to action.
Human action alone is sterile. Yet in concert with the Divine, it is a power above all other strengths. When we accept that, and live it, we become good people.