Religion, Science, and Philosophy

The stories told by Pi both explain events that could have taken place on the lifeboat but Yann Martel was trying to make the point of making the reader see how it is the same thing as religions. The Japanese officials do not believe Pi's story of Richard Parker so Pi gives an alternative version. The Japanese officials have to believe without seeing, that Pi was stuck with the tiger for 227 days. Religions tell stories that are believed even when there is no proof that they ever occurred.
Martel has degrees in religious studies and zoology. Pi experiences both of these throughout the novel. He believes himself to be a Christian, Muslim, and Hindu, and he is very knowledgeable on many animals because of his father and living in a zoo. Pi thinks that the natural world is an expression of God's will, and shows it when he talks about the sloth and how it reminds him of God. Also, there is a conversation in the novel where they guy in India says he has a story that will make people believe in God because the fact that Pi somehow survived the experience is a gift from God.
Finally, since Pi has so much time to himself on the boat he is able to contemplate many philosophical topics such as the meaning of life and God, and also write about them.