In Elie Wiesel's Night, the author writes of his experiences in the death camps during World War II, giving testimony to the horrors prisoners endured. Elie's experiences did not cause him to lose all faith, but to become doubtful about a just and merciful G-d. He also rejected the religious life he led before the camp and rebelled against what he perceived as a distant, silent G-d.

In the original Yiddish manuscript, Wiesel explains the transformation from innocent acceptance of G-d and goodness to skepticism and doubt. He wrote:

In the beginning there was faith—which is childish; trust—which is vain; and illusion—which is dangerous. We believed in God, trusted in man, and lived with the illusion that every one of us has been entrusted with a sacred spark from the Shekhinah's flame; that every one of us carries in his eyes and in his soul a reflection of God's image. That was the source if not the cause of all our ordeals.

Upon first entering Auschwitz, he writes,

For the first time, I felt anger rising within me. Why should I sanctify His name? The Almighty, the eternal and terrible Master of the Universe, chose to be silent. What was there to thank Him for?...Never shall I forget those moments that murdered my God and my soul and turned my dreams to ashes. Never shall I forget those things, even were I condemned to live as long as God Himself (33).

On page 45, he confirms that he does not deny G-d's existence. He writes,

Some of the men spoke of God: His mysterious ways, the sins of the Jewish people, and the redemption to come. As for me, I had ceased to pray. I concurred with Job! I was not denying His existence, but I doubted His absolute justice.

Others prisoners in Night lose faith too. A young boy who was beloved by the inmates is hanged. It soon becomes apparent that the boy is not dead, but hanging from the noose and dying slowly. Another inmate questions his own faith in G-d on page 65:

Behind me, I heard the same man asking: "For God's sake, where is God?" And from within me, I heard a voice answer: "Where He is? This is where—hanging here from this gallows..."

As the inmates prepare to celebrate the Jewish New Year, on page 66 Wiesel asks himself,

What are You, my God? I thought angrily. How do You compare to this stricken mass gathered to affirm to You their faith, their anger, their defiance? What does Your grandeur mean, Master of the Universe, in the face of all this cowardice, this decay, and this misery? Why do you go on troubling these poor people's wounded minds, their ailing bodies?

Wiesel thinks to himself:

I felt very strong. I was the accuser, God the accused. My eyes had opened and I was alone, terribly alone in a world without God, without man...I felt myself to be stronger than this Almighty to whom my life had been bound for so long. In the midst of these men assembled for prayer, I felt like an observer, a stranger.

He rebels against G-d. Elie decides not to fast on Yom Kippur and notes on page 69, “There was no longer any reason for me to fast. I no longer accepted God's silence. As I swallowed my ration of soup, I turned that act into a symbol of rebellion, of protest against Him.”

Another inmate, Akiba Drumer, also loses faith. Elie writes on page 76,

He was not alone in having lost his faith during those days of selection. I knew a rabbi, from a small town in Poland. He was old and bent, his lips constantly trembling. He was always praying, in the block, at work, in the ranks. He recited entire pages from the Talmud, arguing with himself, asking and answering himself endless questions. One day, he said to me: "It's over. God is no longer with us."

Elie does not necessarily lose his faith in the existence of God, but he does come to deeply doubt that God is entirely good after what he experiences in the camps. Elie is initially a devout Jew interested in the Kabbalah (a branch of Jewish mysticism), which is seen as strange for a teenage boy; however, once he is forced into the camps, this faith erodes.

Elie's loss of faith begins when he sees the Nazi guards murdering small children via fire. He cannot believe that a good God would allow children to be brutally slaughtered in this way.

Elie becomes angry with God and tries to rebel against God in any small way he can, even by refusing to fast:

there was no longer any reason for me to fast. I no longer accepted God’s silence. As I swallowed my ration of soup, I turned that act into a symbol of rebellion, or protest against Him.

It is as if Elie views God as complicit in the atrocities against his people.

Other characters lose their faith as well, most disturbingly the most religious among them. For example, Polish rabbi who used to recite his prayers constantly decides God no longer cares about anyone in the camps. Akiba Drumer, once stirring hope in inmates with his beautiful singing of Hasidic songs, gives up all faith in God when he is selected at Block 36. Their pain overcomes any faith they previously had.

Elie Wiesel lost his faith in the goodness and justice of God. Through the horrors of the concentration camps, Wiesel experienced a loss of faith. He was so devastated by the gas chambers, the crematories, and the hangings until he felt a part of him died:   

"Never shall I forget those moments which murdered my god and my soul and turned my dreams to dust..."(pg 32).

Innocent Jews were tortured in the most horrendous ways possible. Elie himself was starved. He and father were barely surviving. Elie witnessed his father being beaten unmercifully by not only the Nazis, but also the other Jews would beat his father because he could not go outside to relieve himself.

Elie witnessed a Jewish father and son kill one another over a piece of bread. This disturbed Elie so much until he gave up all hope and stopped believing in the goodness of God. Elie lost his praise:

"Why should I bless his name? The eternal, lord of the universe, the all-powerful and terrible was silent. What had I to thank him for?" (31).

Elie lost faith in God's justice. He watched innocent Jews die without God's intervention. How could God be fair when innocent Jews were being killed by the millions:  

"I did not deny god's existence, but I doubted his absolute justice..."(pg 42).

Watching innocent Jews being consumed by flames scarred Elie forever. He knew that the Nazis were wrong. The Nazis were evil. There was nothing that Elie could do to change his family's situation. He lost his mother and sister in the flames:

"Never shall I forget those flames which consumed my faith forever..."(pg 32). 

In the end, Elie was reduced to a skeleton of a human being. He was so starved until he could only think about food. He did not even weep when his father died. He was even relieved in a way to know that his father would no longer be a burden. He stopped praying. He became so distant from god. He questioned god:

"Where is the divine Mercy? Where is God? How can I believe, how can anyone believe, in this merciful God?" (73). 

Elie was not the only one to lose his faith. Even the most devout religious Jews begin to lose their faith.  Akiba Drumer loses his faith when he does not make the selection. A rabbi from Poland loses his faith. He had always recited the Talmud from memory, but he concludes that God is no longer with them. "For some, losing their faith in God is akin to losing their will to live." No doubt, it would have been near to impossible to keep the faith in the conditions the Jews faced in the concentration camps.