Although it is a cliche to say that Defoe's The Life and and Adventures of Robinson Crusoe of York, Mariner (1719) is a spiritual biography, the novel is just that: before his ill-fated voyage, Crusoe is at odds with both his father and his God,
and my conscience, which was not yet come to the pitch of hardness to which it has since, reproached me with the contempt of advice, and the breach of my duty to God and my father (http://www2.hn.psu.edu/faculty/jmanis/defoe/crusoe.pdf (7),
and at the conclusion of his voyage, he comments that his life has been characterized, so far, "Providence's chequer-work" (259), acknowledging the role of God in the outcome of his adventures.
At many points after Crusoe's religious conversion, he makes very conventional statements about "God's grace" and the "power of Providence" as an integral part of his life. These are statements that any outwardly religious person might make on a daily basis, but in his fourth year on the island, Crusoe discusses his view of himself in the world:
I looked now upon the world as a thing remote, which I had nothing to do with, no expectations from, and, indeed, no desires about: in a word, I had nothing indeed to do with it.... (111)
This is a startling statement for a man with Crusoe's upbringing and acquisitive nature to make: in addition to his conventional Christian beliefs, and his comments one would expect a conventional Christian to make, Crusoe has decided that he no longer belongs to the world of Robinson Crusoe, Mariner. He has, in effect, renounced his place in the world of his father, his earthly father, and quotes Abraham's comment to Dives, "'Between me and thee is a great gulf fixed." (112)
Another watershed religious experience is, of course, Crusoe's conversion from an observer of Christianity to one who practices Christianity. When he reads the words "He is exalted a Prince and a Saviour, to give repentance and to give remission," (84) Crusoe has what is called an epiphany, a light goes on in his brain and soul and he is converted not to a religion in name only but to a set of beliefs that he tries to practice from that point forward.
Soon after his conversion experience, Crusoe considers the line "Call on Me, and I will deliver thee," which might be Defoe's mistake for Jeremiah 33:3 ("Call unto me, and I will answer"), but this leads Crusoe to examine what "deliver" means. In the past, his concept of deliverance is restricted to being delivered from his predicament on the island. Now, with his conversion experience just behind him, it occurs to him that the word deliver applies to his soul, his being, rather than his situation:
I looked back upon my past life with such horror, and my sins appeared so dreadful, that my soul sought nothing of God but deliverance from the load of guilt that bore down all my comfort. . . . (84)
Rather than looking to God to get him off the island, which he says "was certainly a prison to me," he recognizes that the important deliverance is not from his physical setting but his spiritual isolation from God.
These three defining moments of Crusoe's religious experience coalesce to create within Crusoe the new man, a spiritual being who, despite some lingering religious superficialities as an example of 18thC. England, tries his best throughout his stay on the island (and afterward) to remain a true believer in God's grace.