Gertraud “Traudl” Wallbrecher was nine years old when Hitler rose to power in her native Germany, and sixteen when World War II began. As the leader of a Catholic Youth Movement group of girls, she experienced firsthand the terrors of dictatorship, risking her life in the underground resistance. At the same time, she saw how many churchgoing Christians succumbed to Hitler’s ideology out of fear, opportunism, or conviction.

Drafted into military service in a hospital near Munich in 1945, she was brought face to face with the horrifying extent of Nazi brutality when she witnessed the evacuation of the Dachau concentration camp. For the rest of her life, the horror she had seen kept her asking: “How could this crime – especially the mass murder of my Jewish fellow citizens – have happened in a country that is so thoroughly Christian? Why wasn’t the church strong enough to mount an effective resistance?”

After the war, Wallbrecher hoped that the restoration of civil liberties, including religious freedom, would be accompanied by a wave of deep-going repentance and revival. Yet that is not what happened. Instead, she watched as an unprecedented, silent exodus from the church began – a process of de-Christianization whose contours are only now becoming clear.