Who does David choose to be his God and why?

In Chapter Three, David decides that he should have a god to help him during the hard times. He considers the different gods that the men and women at the camp prayed to for help, and he decides that he will pray to the god Johannes had talked to him about..... the God, the God of a man in the Bible who is also named David. David begins his prayer by "God of the green pastures and the still waters", and he finishes his prayer with "I am David. Amen." David continues to begin and end his prayers in this way throughout the novel. He believes that his prayers give him greater strength, as well as the courage to move on.