In Life of Pi, what 3 religions does Pi follow and why?

Pi is an interesting kid, because he finds much to be
admired in many different religions, and decides to become members of three prominent
ones.  This disturbs his parents, and the leaders of each individual church he attends,
but Pi finds elements that are wonderful in each of
them.

Pi joins the Christian faith, the Muslim faith, and
the Hindu faith.  In each one, he likes different aspects of it.  In Christianity, it
was Jesus Christ and His ultimate sacrifice that appealed to Pi.  It was illogical but
touching, and that selflessness really moved him. He said that it was Jesus' "humanity
that I found so compelling," and after thinking about Christ and his sacrifice of self
for sins for three days, he was hooked.  That was the main appeal for Christianity--the
love apparent in that act.  His attraction to the Muslim faith was centered in its
"religion of brotherhood and devotion," to its calisthenics, its open-aired temples that
was open "to God, to breeze," and how it felt good to pray so often.  Hinduism appealed
to him because of its many sensory elements, and because of the element of Karma and a
larger universe that is "aware" of all things.

Each of
these religions held a special and very moving place in Pi's heart, and the bottom line
was that the existence of God--in whatever form--was a great comfort and strength to
him.  Martel insists that is one of the functions of religion--to tell a story that
provides humans with strength and comfort, as they did for Pi.  I hope that helped; good
luck!