The nature and definition of morality is a basis for one of the arguments that is used in Apologetics to establish the existence of God. Here is an article on the definition and nature of morals:
Morality, Absolute Nature of. Orthodox Christianity has always defended moral absolutes. However, most modern ethicists hold some form of relativism. Thus, it is necessary to defend the belief in moral absolutes.
Moral Absolutes. Before the absolute nature of morality can be understood, morality must be defined. Several things are meant by a moral obligation. First, a moral duty is good in itself (an end), not merely good as a means. Further, it is something we ought to pursue, a duty. Morality is prescriptive (an “ought”), not merely descriptive (an “is”). Morality deals with what is right, as opposed to wrong. It is an obligation, that for which a person is accountable.
An absolute moral obligation is:
an objective (not subjective) moral duty—a duty for all persons.
an eternal (not temporal) obligation—a duty at all times.
a universal (not local) obligation—a duty for all places.
An absolute duty is one that is binding on all persons at all times in all places.
Defense of Absolutes. Moral absolutes can be defended by showing the deficiency of moral relativism. For either there is a moral absolute or else everything is morally relative. Hence, if relativism is wrong, then there must be an absolute basis for morality.
Everything is relative to an absolute. Simply by asking, “Relative to what?” it is easy to see that total relativism is inadequate. It can’t be relative to the relative. In that case it could not be relative at all, ad infinitum, since there would be nothing to which it was relative, etc. Albert Einstein did not believe everything was relative in the physical universe. He believed the speed of light is absolute.
Measurement is impossible without absolutes. Even moral relativists make such statements as, “The world is getting better (or worse).” But it is not possible to know it is getting “better” unless we know what is “Best.” Less than perfect is only measurable against a Perfect. Hence, all objective moral judgments imply an absolute moral standard by which they can be measured.
Moral disagreements demand objective standards. Real moral disagreements are not possible without an absolute moral standard by which both sides can be measured. Otherwise both sides of every moral dispute are right. But opposites cannot both be right. For example, “Hitler was an evil man” vs. “Hitler was not an evil man” cannot both be true in the same sense (see First Principles). Unless there is an objective moral standard by which Hitler’s actions can be weighed, we cannot know that he was evil.
Moral absolutes are unavoidable. Total moral relativism reduces to statements such as “You should never say never,” “You should always avoid using always,” or “You absolutely ought not believe in moral absolutes.” “Ought” statements are moral statements, and “ought never” statements are absolute moral statements. So, there is no way to avoid moral absolutes without affirming a moral absolute. Total moral relativism is self-defeating.
Geisler, N. L. (1999). In Baker encyclopedia of Christian apologetics (p. 501). Grand Rapids, MI: Baker Books.