After losing his (David's) compass, David decided he must have a God. What purpose would a God serve?

As he prepares to leave, however, he slips on a rock and drops his compass into the sea. He immediately becomes desperately worried about how he will manage without it, and says, out loud, "Oh God" (see "Quotes," p. 55). This leads him to consider that maybe he should have a god to help him through difficult times, and after considering the various gods prayed to by the men and women in the camp, decides to pray to the god spoken of by Johannes - the God, narration describes, of a man in the Bible also named David. This David starts his prayer by "God of the green pastures and the still waters", and concludes by saying, "I am David. Amen." Tthis is how he starts and ends all his prayers throughout the book. He then feels greater strength and the courage to keep traveling.