Moral relativism is the view that when it comes to questions of morality, there are no absolutes and no objective right or wrong; moral rules are merely personal preferences and/or the result of one’s cultural, sexual, or ethnic orientation. The fact that one believes there are exceptions or, to be more precise, exemptions to moral rules does not make one a moral relativist. For example, many people who believe lying is wrong nonetheless believe it is not wrong to lie in order to protect someone’s life. These people are not moral relativists, for to permit certain exemptions to a rule one must first acknowledge the general validity of the rule. The moral relativist rejects the idea that any such moral rules exist at all.
— Francis Beckwith, from Why I Am a Christian: Leading Thinkers Explain Why They Believe, Norman Geisler and Paul Hoffman, eds., chapter 1