I believe this term “agnostic” is used to identify those we call as “athiests” — because I don’t believe it is possible for most people to be true “athiests” as in not believing in a greater power than themselves. People replace religion with belief in something else — nationalism, shopping, tv etc. — it’s in human nature.
Since Adam and Eve tried to hide in the garden it has been the natural inclination of man to run from God.