For the first third of the book being entirely about Pi's devotion to religion in different forms, the rest of the book is surpisingly sparse on any religious commentary or references. While Pi is in the lifeboat, Martel hardly ever describes him thinking about God. The first mention is in chapter 53, a couple pages in. Pi is hopeless, and facing the realization that he will most likely die. But then a voice in his head says that he will survive, he will not die, "as long as God is with me, I will not die. Amen." This resolves him, and he starts planning for survival, instead of moping or cowering in fear.
At the very end of chapter 60, he discusses some Hindu symbolism to describe how insignifican the feels, then "mumbled words of Muslim prayer and went back to sleep." He is able to fall asleep, to be comforted by his prayers. In chapter 63, he lists his daily routine, and prayer shows up several times, so it was obviously on his mind. In chapter 74, he describes religious rituals he practiced. He says, "Faith in God is an opening up, a letting go, a deep trust, a free act of love-but sometimes it was so hard to love." He goes on to describe his fear of losing faith, of sinking "to the very bottom of the Pacific." But after this, he says that his faith always remained, "a shining point of light in my heart."
Those are just a few to get you started; I hope they help!