Daniel Defoe's novel is, at its core, the spiritual autobiography of one man: Robinson Crusoe, mariner of York. He is first rebellious, then atones for his sins, and then converts himself and others to Christianity. We begin the novel with Crusoe's rebellion: defiance of his father's plan for him, an act that is framed as going against the authority of God himself. Crusoe then suffers the vicissitudes of fate – a series of misfortunes that land him on the deserted island. Once there, he finally atones for his sins and undergoes a serious religious conversion. The novel then becomes a collection of religious observations. We see Crusoe turn into a teacher, as he converts Friday upon meeting the guy.
Besides the redemptive structure of Robinson Crusoe, we can see many Biblical themes developed in the novel. For example, Crusoe's own story is very much like the parable of the parable of the prodigal son. The character of Crusoe is also pretty similar to such Biblical figures as Jonah (the one who was swallowed by a whale/giant fish) or Job (the guy who loses everything and everyone he loves) who have their faith tested through many trials and a tremendous amount of suffering.
This book suggests that religion is the foundational force is a person's life.
While religion is an important part of life, this book suggests that we should be tolerant of other religions and cultures.