Elie experiences a renewal of faith. why? what incident brought him to this?

Ellie is a strong believer in God who struggles mentally and physically. Ellie's faith is shaken by the cruelty and evil witnessed at the Nazi concentration camps during the Holocaust. He questions how the cruelty and horrors experienced at the camps could reflect divinity and wonders why a divine God could allow such cruelty to take place.
Several events occurred that made him renew his hope and faith in God: He was able to remain with his father, keep his shoes and stay alive while others were sent to immediate death. Innocent Jews were tortured in the most horrendous ways possible, Ellie was starved and witnessed his father being bitten by the Nazis and Jews. Though he claims not to believe in God, he prays when his father dies.