What is Krebs' relationship with God prewar and postwar?

Although the story does not explicitly describe Krebs' relationship with God prior to the war, the text provides an important hint.
When his mother begs him to pray with her, Krebs refuses. He tells her that he cannot pray. It is apparent from his mother's actions that it is not unusual for them to pray together.
At present, however, Krebs' refusal to pray shocks and dismays her. At one stage, Krebs even tells his mother that he does not love her. His honesty shocks her, but Krebs is telling the truth. He feels estranged from both God and family.
Today, we would say that Krebs suffers from post-traumatic stress disorder (PTSD). Soldiers who suffer from PTSD often find it difficult to engage in the normal activities most people take for granted. Like Krebs, they may also harbor negative thoughts and perspectives about life.
To answer your question, Krebs' prewar relationship with God differs from his postwar relationship with God. While there is every indication that he may have had a strong relationship with God before the war, Krebs now has a nonexistent relationship with God. Trauma-related stress has weakened his religious inclinations.
https://www.ptsd.va.gov/public/ptsd-overview/basics/what-is-ptsd.asp