Which of Pi's spiritual teachers impact him the most? Why are they important and how to they impact him?

I think Pi was not partial to any one religion in particular. This is perhaps one of the major themes in the story. Pi simply likes to explore the eternal possibilities of faith and wisdom. In the rather funny scene when all three religious figures meet in front of Pi's house, a rather embarrassed Pi says,

"Bapu Gandhi said, 'All religions are true.' I just want to love God," I blurted out, and looked down, red in the face."

Pi wasn't spiritual at all!