Morality reveals God's existence. Why? Because morality implies that humans are good and valuable beings. What is the origin of this? Accidental natural forces or an intentional being who is good by nature. 
There are a couple of responses that we may hear from unbelievers in response to the moral argument. First, the Euthyphro dilemma will force us to examine God's relation to goodness. Second, there is the problem of morally bad people possibly going to heaven, which forces us to look at the demands of moral justice in light of an afterlife.