"What is the Moral argument for the existence of God?"
Answer: The moral argument begins with the fact that all people recognize some moral code (that some things are right, and some things are wrong). Every time we argue over right and wrong, we appeal to a higher law that we assume everyone is aware of, holds to, and is not free to arbitrarily change. Right and wrong imply a higher standard or law, and law requires a lawgiver. Because the Moral Law transcends humanity, this universal law requires a universal lawgiver. This, it is argued, is God.
In support of the moral argument, we see that even the most remote tribes who have been cut off from the rest of civilization observe a moral code similar to everyone else's. Although differences certainly exist in civil matters, virtues like bravery and loyalty and vices like greed and cowardice are universal. If man were responsible for that code, it would differ as much as every other thing that man has invented. Further, it is not simply a record of what mankind does—rarely do people ever live up to their own moral code. Where, then, do we get these ideas of what should be done? Romans 2:14-15 says that the moral law (or conscience) comes from an ultimate lawgiver above man. If this is true, then we would expect to find exactly what we have observed. This lawgiver is God.
To put it negatively, atheism provides no basis for morality, no hope, and no meaning for life. While this does not disprove atheism by itself, if the logical outworking of a belief system fails to account for what we instinctively know to be true, it ought to be discarded. Without God there would be no objective basis for morality, no life, and no reason to live it. Yet all these things do exist, and so does God. Thus, the moral argument for the existence of God.