Vocal faithfuls will tell you that they are good because there is this "someone" who they consider like a Summum Bonum, that is the the sum of all good wherein every little good came from. Just because they believe in a God, they consider themselves morally stable. Comparing to atheists who don't rely in some so called moral source, the faithful has a bench mark, a standard they attribute to God, who they consider to be the one who created them and set the standards of right and wrong, good and evil.
Now I question, how can this God they believe communicate to each and every believer? If they consider their morals by and for God, how can they know that the things they do really please God or at least if the morals established in them are really from God. Those who say that the Bible did this role is a complete idiot because the moral standards of modern Christianity is far more advanced than that of early Judaism and early Christianity. For example, killing a gentile is an act of worshiping God in the old testament, so is praying for the death of your enemies something acceptable to God. Jesus in the New testament actually changed this (I wonder why the son is less violent than his father), He taught all about love including loving your enemy. No matter how better his teachings are than his father, he still failed in some issues. He failed to teach women's rights and he is one good example of a communist (If you are already good, sell all your possesions and give your money to the poor). A God must be perfect. This teachings are not entirely morally acceptable to the modern man, thus imperfect. Therefore Jesus is not God nor is the Bible a source of Morals.
Some might say, "O God communicates through my conscience." Well, this will lead me to a second point. Why does each believer has his own version of this standard which they consider coming from a single source? Well if there is such thing as absolute goodness and absolute evil whose standards are set by a supernatural being, then there should be agreement as to what is good and what is evil among those who believe in the same deity. In the status quo, people who believe in Yahweh can't even agree on issues of morality. Liberal theists think its okay to use contraceptives and that divorce is inevitable. Conservatives believe that only those who believe in Jesus can be saved, etc. etc. etc. It is clear that there is no agreement on what is morally acceptable among the believers.
So where do I get my morality from? Now, let me throw the same question to every believer for it is clear that, at the end of the day, we, the people get our morals from our own conscience, our conscience conditioned by some norms of the society and genetic predispositions. Nothing supernatural about that. So the next time a believer claims moral superiority as a consequence of the belief in God, that's a very big shame indeed.