A moral obligation is a duty; it is something one ought to do or forbear. To say you have a moral duty not to steal is to say that you ought not steal. This duty must be based on some principle. To claim that one ought not steal because there is an innate feeling of shame that comes with stealing is a non sequitur. There may be such a feeling but it does not follow logically from the fact that there is that one ought not steal. You might say that if you don't want to feel shame, don't steal. But that is not the same as saying you have a moral obligation not to steal. You might say that you must obey God's will and God's will is that you not steal. This is called the divine command theory of moral obligation. It is meaningless to those of us who do not believe there is such a being as a god. You might say that you should always do what will bring about the greatest happiness to the greatest number. You might then claim that you have a moral duty not to steal because not stealing leads to the greatest good to the greatest number. But, if you do not accept the greatest happiness principle, then you will not accept that your duty not to steal derives from it. You might believe that you should only do what you could will that anyone in the same situation should do. You then might conclude that you ought not steal because you could never will that others in your situation steal. But if you don't accept the principle that you ought only do what you can will that anyone should do in the same situation, then you will not accept that your duty not steal derives from that principle. But you can never logically derive that you ought not steal from a feeling. If that were the case, then anything you feel like doing is morally justified, which is absurd.