Faith provides the foundation for the plot of the novel and helps to establish the character of Pi. To help you understand the importance of faith and religion in Life of Pi, you can start by reading the "Life of Pi Themes" section within eNotes. As the author of that document notes, each character in the novel is looking for his/her purpose in life and is thus searching for life's meaning. Such is the essence of faith and religion.
As you prepare to write your essay, locate 2-3 quotes from Pi that reveal his need to find meaning in life and his concerns about religion. One quote could come from his dialogue with his parents about his practicing several religions at once. [As you read in the book, before Pi and his family leave India for Canada, Pi becomes a student of religion: born a Hindu, he meets Father Martin and discovers Catholicism at the age of fourteen. After being baptized a Catholic, he meets Mr. Kumar and converts to Islam. When his parents ask him how he could possibly follow all three religious systems, Pi answers them by quoting Gandhi. From an early age, then, Pi demonstrates the importance of faith and religion to him through his actions and his discussions with his parents.]
To survive 227 days on a lifeboat on the ocean is proof of Pi's deep faith. Had he not believed in a greater power and had faith in this power's support of Pi's existence. Modern psychology postulates that people of faith are better survivors: they tend to be able to weather personal hardships better than do their non-believing friends. You can insert and explain a quote from Pi when he is on the lifeboat with Richard Parker and is considering his plight. Make certain that the quote you select clearly connects to Pi's faith and in his being able to persist under truly adverse conditions.
In organizing your essay, present general background on the novel in your introduction. Mention its title, author, and a general statement about a theme or the plot of the novel. The last sentence in your introduction should present your thesis and could read something like this: Beginning in his early adolescence, Pi revealed strong faith and a predilection for religious study; it is this faith that sustained him throughout his ordeal in the lifeboat.
As you move into the body of your essay, focus on Pi's religious nature before he and his family began their move to Canada and then discuss the importance of his faith to Pi's survival at sea. Conclude by reiterating your thesis (use different words, but maintain the gist of your statement) and bring your essay to closure with general statements about the importance of faith to survival. Include textual support for the points you make in the body of your essay, and do not introduce new information in the conclusion.