Akiba is initially an exemplar of the unshakable faith many of the Jews sustained in the midst of the Holocaust. He tells the others that "God is testing us" and that the Jewish people have not really been abandoned. Later, we are told that Akiba has lost his faith and, for that reason, has become a victim of "the selection"—meaning that he'll be killed. The others promise that, in three days—when he knows that he'll be dead—they will say Kaddish for him. But when the time comes, they simply forget to do so.
Obviously (and understandably), the inmates have themselves lost their faith. What is surprising is that they had kept it as long as they did. The central question that Wiesel poses is: what keeps people believing for so long, especially under circumstances where a justifiable (even natural) reaction would be to think that God has abandoned them? The fact that the men "forgot" to say Kaddish implies that their loss of faith is still an unacknowledged one.
Eliezer (Wiesel's autobiographical character in the novel) continually struggles with himself over the question of why God would allow such things to happen. In the end, there is no answer. The case of Akiba Drumer is emblematic of this dilemma—at the heart of the story. But Wiesel frames the story within his own, personal religious context. Before he and the other Jews of Sighet were deported, his principal activity was to study Kabbalah. Akiba is thus a kind of mirror of Eliezer, and the fact that Eliezer survives and Akiba does not illustrates the randomness and meaninglessness of the atrocity of war and genocide—but also of life in general.