In Life of Pi, storytelling and religion are closely related because of the main character's understanding of stories and his three different religious faiths.
Pi follows Hinduism, Christianity, and Islam. His entry into Christianity is, notably, the story of Jesus. He falls in love with the story, despite not understanding the choices that Jesus made. For each religion that he follows, though, Pi understands its tenets and benefits through stories. He remembers stories from his own life and collects stories from his guides in each religion.
Storytelling is one thing that helps get Pi through his journey. He is able to frame his experiences in a different way because stories don't always have to be exactly true—it all comes down to helping another person understand something. In this way, the story of Pi's journey can help others understand what happened without him having to relive the actual horrors of it. This way of teaching through stories is a skill that he learned from studying his different faiths; each one told a story about love. It didn't matter that the stories were different. It only mattered that they all arrived at the same point.
Religion is made up of stories. Pi's faith in these stories and his beliefs are a major reason why he was able to survive and live with his experience. This is shown when he tells the investigators a version of his story with animals and then, after they are unwilling to believe him, tells them the version with humans. They ultimately decide they prefer the one with animals.