Robinson crusoe's preface stresses the story's religious meaning that Defoe wished his hero to undergo moral as well as physical trails for Defoe as a full human being must evolve spiritually as well as survive physically.
Defoe called the book 'allegorical' probably because ,within the adventures, lies a moral version of life.Crusoe from the start suggest some strange inner meaning concerning his 'sin' of disobedience against his father.His sin according to him is self-willed therefore deserving of punishment.He therefore takes the storm for a plain token of god's anger.
Though he has shunned God willingly yet he is brought back by severe experiences and by reflecting at the mercy of God, thinks of the distinguishing goodness of him being singled out from the storm.The reason he survives is something explainable only by god alone.
Suffering from ague, he repents the wickedness which provoked the justice of god.later'seeing the footprints he thinks that his landing on the island's safer side means some special providence saving him for a divine purpose.Bible texts help him though at first he lacks conviction-yet the sprouting barley,earthquake,hurricane and dream move him towards conversion.In distress he prays fervently and decides that' deliverance from sin 'far outweighs 'deliverance from affliction.'.
At last,he trusts in God,though for a while the footprints frightens him into uncertainty.With assurance renewed,he converts Friday,and 'a secret joy' floods his soul.
However intent Defoe was on imagining the island's adventures,he was moved also by the theme of a soul finding it's spiritual allegiance.