Pi's Impending Tragedy as the Narrative Engine

Although the beginning of this book is filled with the details of Pi's youth, it is made known from the very beginning that some sort of tragedy happens and changes his whole life. In the very first chapter he talks about how much he has suffered, how he could barely walk or eat, as well as the emotional trauma he has. The reader knows something terrible is coming; it just has to be set up. Of course, if one reads the back of the book it gives away what happens, but even still, the reader doesn't know how that circumstance comes to be or how Pi survives it. Just enough allusion is given to keep the reader interested. I find myself thinking of how everything he loves and talks about will be gone before too long, he just doesn't know it at the time of the beginning of the story, and it makes those little details bittersweet. I also find myself impatient to get to the part about the ship sinking, to find out what happens. I want to find out why this is a story 'to make you believe in God." Is it only because Pi survives a seemingly-impossible situation? Or is there more to it? I suspect there is, since Pi seems so interested and all-believing in religion. I'm anxious to find out what this story is all about, so the narrative engine is definitely working.