Chapter 5 brings one of the strongest denunciations from Eliezer regarding the presence of God. The arrival of Rosh Hashanah prompts Eliezer to launch into a pointed and brutal tirade about where God is in the Holocaust. It is a significant point because there has not been such a pronounced and defining break with the divine. From someone who studied the spiritual and nuanced elements Judaism with Moshe the Beadle to this is a dramatic and profound shift of advocacy. It is representative of the results of the Holocaust and all that Eliezer has had to witness.
The presence of the selection and the terror that goes into a process is also detailed in Chapter 5. Eliezer struggles to run past the doctors so quickly that his number cannot be written down and thus cannot be "selected." It is significant because his fears about the selection exist on two levels. He is worried about his own "selection" and his father's. Eliezer recognizes that he must worry for both of the because his father is moving into a position where he cannot fend for himself as much as he used to. Adding to this would be how Eliezer becomes wounded in his foot, requiring operation and extended time in the infirmary. These details add a visceral and brutal level to Eleizer's time in the camps. He is getting to a point where survival is the only instinct he will have left within hm and Chapter 5 illuminates such a condition.