The theme of this book is maintaining faith .
At the beginning of the work, his faith in God is absolute. When asked why he prays to God, he answers, “Why did I pray? . . . Why did I live? Why did I breathe?"His faith is grounded in the idea that God is everywhere, all the time, that his divinity touches every aspect of his daily life. He believes God is omnipresent. Eliezer’s faith is irreparably shaken, however, by the cruelty and evil he witnesses during the Holocaust. He begins to question his God because he hasn't came to help him.He wonders how his God could be part of such depravity and how an omnipresent God could permit such cruelty to take place.
His faith is equally shaken by the cruelty and selfishness he sees among the prisoners. Eliezer manages to retain some of this faith throughout his experiences. During his first night in the camp and during the hanging of the pipel Eliezer does grapple with his faith but he didn't abandon his faith. When Eliezer says that he has given up on God completely, Wiesel’s constant use of religious metaphors helps what Eliezer says he believes. Eliezer even refers to biblical passages when he denies his faith. When Moshe the Beadle is asked why he prays, he replies, “I pray to the God within me that He will give me the strength to ask Him the right questions.” In other words, questioning is fundamental to the idea of faith in God.
When he fears that he might abandon his father, he prays to God, and, after his father’s death, he expresses regret that there was no religious memorial.At the end of the book, even though he has been forever changed by his Holocaust experience, Eliezer emerges with his faith intact.