Explain why Eliezer felt angered for the first time. Why is this significant?

In Chapter Three, Eliezer watches in horror as a truck full of children drives up to a giant, fiery ditch and the children are put into the flames. Eliezer's father is sad that he is going to see his only son consumed by fire, and he tells Eliezer that humanity is not present in the concentration camps. As the parade of men starts to recite the prayer for the dead for themselves and his father begins to weep, for the first time Eliezer feels himself revolt against God.