What is the main conflict in Illusions: The Adventures of a Reluctant Messiah by Richard Bach?

Two itinerant fliers meet on a Midwestern field and the one, a retired Messiah, Donald W. Shimoda, teaches the other, the narrator, Richard, how to see the world and everything in it as illusion. The teacher is assassinated, and the pupil records his story before facing his own destiny as another reluctant messiah.