Moral relativism is more easily understood in comparison to moral absolutism. Absolutism claims that morality relies on universal principles (natural law, conscience). Christian absolutists believe that God is the ultimate source of our common morality, and that it is, therefore, as unchanging as He is. Moral relativism asserts that morality is not based on any absolute standard. Rather, ethical “truths” depend on variables such as the situation, culture, one's feelings, etc.
Several things can be said of the arguments for moral relativism which demonstrate their dubious nature. First, while many of the arguments used in the attempt to support relativism might sound good at first, there is a logical contradiction inherent in all of them because they all propose the “right” moral scheme—the one we all ought to follow. But this itself is absolutism. Second, even so-called relativists reject relativism in most cases. They would not say that a murderer or rapist is free from guilt so long as he did not violate his own standards.
READ MORE: http://www.gotquestions.org/moral-relativism.html