Elie had not lost faith in God when he arrived to the camps he still belived that there was a God that was causing all this and he still prayed to that God but it was later in the book when he startes to question God’s existance.
When they arrived at the camp Elie and is dad get pointed to the same side thats when the gaurd tells them and the rest of the group that they are going to the creamatory but then that group didn’t go to the creamotory they went to go work while the other group went to the cremotory some people before entering were reciting the prayer for the dead. Even thought they were in a tough situation they were reciting that prayer for themselves thinking that they were going to die at that point even Elie was reciting that same prayer for himself even though some including himself thought that God had left them.
In the book there are many parts when people in their toughest times they ask and come back to God for help. Scenes that demonstrate this is when Elie notices what Rabbi Lihues son just did to his father, at the arrival of the camp, and during selection to who gets to live and who goes to the