Agnosticism is a middle position concerning belief in the divine. Theists believe in the existence of God, or the reality of, in the words of Joseph Campbell, an "invisible plane" supporting the visible context of everyday life. Atheists do not. They believe all reality can be explained by scientifically reasoned principles and that there is no reason to postulate spiritual forces beyond perceived phenomena. In short, the material realm of the cosmos contains all that exists (See Anthropomorphism).
The word "agnostic" derives from "gnosis," which means knowledge, or the condition of knowing. An agnostic is one who professes not to know. The word is used in two different religious conceptions:
1. A person may claim that knowledge of God is unknowable to anyone; that God is above human categories of thought and thus impossible to know or understand with human sensibilities. In other words, God may or may not exist, and it is impossible for humans to know.
2. A person may claim that he or she has not experienced the divine and therefore cannot demonstrate personal knowledge of a deity.
Joseph Campbell, author of such books as The Masks of God and The Hero with a Thousand Faces, has associated the words theist and atheist with the tendency to connect religious myth to historical fact. In an interview with Bill Moyers televised by PBS, he somewhat facetiously divided the world into two camps. Those in one camp, he explained, believe their religious myths are historically accurate explanations of how things occurred. These, he said, are called theists. Those in the other group-knowing, for example, that God didn't create the world in six literal days-refuse to acknowledge the historical accuracy of their culture's mythology and are labeled atheists. In Campbell's view, the two words are arbitrary designations based not on belief but rather on mythological interpretation.
Sources: Campbell, Joseph. The Power of Myth. New York: Doubleday, 1988. Webster’s Third New International Dictionary and Seven Language Dictionary. 3 vols. Chicago: William Benton, 1966.