Death is a pervasive element in a story about death camps. Death is fundamental to human society—anthropologists cite burial practices as the foundation of civilization. The Nazi "slaughterhouses" and "factories of death" are antithetical to this civilized practice of death; the Final Solution is an absolute mockery of human rights and values.
This moment of prayer comes right after arriving at Auschwitz—"Haven't you heard about it?"—when the group is being marched "to the crematory." They will not be killed (not yet) but the terror this welcome march inflicts serves to instill despondency, melancholia, and separation of the prisoners from each other. The Germans knew this, they knew that their prisoners could not have empathy: the faster the prisoners live for themselves alone, the faster they die together.
Eliezer grasps the message of their first walk, saying, "[h]umanity is not concerned with us." There is no one to witness their death and no one to mourn them with the right prayer except themselves. Later, when Akiba Drumer is selected for death, he asks them to recite the Khaddish for him—they forget to do so because they are preoccupied with survival.
Death is a major theme in the novel. The cruelty and inhumanity experienced in the camps leads to a lack of mourning among the prisoners. Death is to be avoided at all costs, and the need for survival takes precedence over empathy and mourning for those who have died. Eliezer believes that if there is no empathy or mourning for the dead, than only madness will prevail.
What keeps many going, including Eliezer and his father, is the belief that their loved ones are still alive. Many of the men keep going for the hope that their children will survive and they will be together again. Eliezer and his father fight for survival for each other, as well as the hope the rest of the family is alive.