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

Illusions: The Adventures of a Reluctant Messiah is, above all, about how the entire physical universe in time and space is an illusion. Reality exists, but is divinely indifferent. "The Is" (i.e., God) cares nothing about human illusions and games, views humans as his/her perfect, finished likeness. When modern-day "Reluctant Messiah," Donald W. Shimoda, attracts a disciple, the narrator Richard, Richard begins with simple tricks such as floating tools in the air. Richard recalls being told as a child that magic tricks are illusions. Shimoda explains how any so-called "miracle" becomes possible once one realizes all is illusion. If this is so, Richard initially wonders, why live?