A good way to think about it is to think of the poem "Footprints"(http://www.markhar
The God analysis works because the first hundred pages of the book is all about Pi trying to find God, and his inability to choose a religion. If you look the scene with the Blind Frenchman, the dialogue is very Beckett-like which reinforces the idea of searching for God through Beckett's works such as "Waiting for Godot" or "God."
If you look at the book circle questions at the end of the book, we learn that green is the color of Islam. Martel takes us to the unbelievable extremely green island b/c he wants us to make the leap of faith that is required to accept the sometimes fantastical stories of religions. When Richard Parker comes onto the island ALL the Meerkats look over in his direction in a praying like stance. Then they gleefully allow "God" to devour them with no thought--only the promise of after life. The meerkats facing Richard Parker in prayer can be viewed as the Islamic all praying towards Mecca or "God." It follows that Martel is criticizing suicide bombers with the meerkats--who, foolishly and with no regard for their lives--give themselves to "God's will." Completely comfortable on an Island with no foundation that devours them by night.
In an interview with Ray Suarez, Martel states: "Yeah, except that if you look at religion, what's remarkable is how the mystics of each religion speak the same language. So if you look at the Muslim mystics, the Sufis; if you look at Christian mystics, like St. John of the Cross; and Hindu mystics, it's remarkable how they all speak the same language, which is a language of a personal relationship with god and a language of love, where God is love.
It's once you get further away from the mystics that you start getting differences, which sometime seem unbridgeable. Now, I think those unbridgeable differences are due to dogmas, and sometimes dogmas stray very far way from faith. And the other key thing to point out, too, is that you can kidnap anything, including very good ideas, so there is nothing in Islam that justifies killing innocent people, and yet some Muslims will do that in the name of Islam; just as there are some Christian fundamentalists, for example, here in America who will kill doctors who perform abortions. There's nothing in Christianity that in any way condones that."
The Island is there to make the story step into the unbelievable--make you take the leap of faith, in order to believe the first story.
The tooth represents the animalistic tendency within us and perhaps also the ego, or "shadow;" the island, an obvious allusion to eden, also shows that Pi must now learn to control/overcome these hindrances on his path towards Godhead.
The ending shows how religions may have taken true stories (the second ending)and changed them to be more miraculous because they are the "better stories" (the first ending) than the actual hardships endured. Martel is saying that perhaps it matters not which story "Christianity, Muslim, Buddhist, or Hindu" we choose, because these are just stories to help us understand the true nature of spirituality--rather, what matters is how we incorporate God into our own lives.
But Pi ultimately realizes that God is still with him and was with him always.
In an interview with Martel, after being told "I hope more people read your book," Martel responds: "May Richard Parker always be at your side."
I also find it very interesting that Pi is from Pondicherry--home of the mystic sage Sri Aurobindo.
"'Well, as I understand it, Integral Yoga (developed by Aurobindo)is basically a set of principles to guide one all the time, in every circumstance. I mean, he's written about it in various ways, and there are many dimensions to it, but in its essence, it's actually simple. It comes down to three things, which he called aspiration, rejection, and surrender(sound familiar). So first, you have to aspire one-pointedly to realize the Divine with your whole being. And although this aspiration can start as simply a mental act of will and intention, it ultimately has to come from a much deeper place, from your own soul's longing for that divine perfection. Then, when he speaks of rejection, he's saying that you have to reject anything that arises within you or outside of you that would obstruct the fulfillment of your aspiration. Granted, at first the subtlety of what to reject and what not to reject might not be so obvious. But if your aspiration is genuine, you will fairly quickly come to a place where it's easy to see directly what is a help and what is a hindrance. And then your aspiration is tested because you have to be willing to make the right choice.'"