On a recent visit to Virginia I met one of my heroes: Jürgen Moltmann. I have plowed through almost a dozen of his books, and to my surprise, the German theologian in person exuded a charm and sense of humor that belie his scholarly works.

Moltmann was planning on a career in quantum physics until he was drafted at age 18 at the height of the Second World War. Assigned to anti-aircraft batteries in Hamburg, he saw compatriots incinerated in the fire-bombings there. The question "Why did I survive?" haunted him.

After surrendering to the British, the young soldier spent the next three years in prison camps in Belgium, Scotland, and England. When Hitler's empire imploded, exposing the moral rot at the center of the Third Reich, Moltmann saw how other German prisoners "collapsed inwardly, how they gave up all hope, sickening for the lack of it, some of them dying." As he learned the truth about the Nazis, Moltmann felt an inconsolable grief about life, "weighed down by the somber burden of a guilt which could never be paid off."

Moltmann had no Christian background. He had brought two books with him into battle—Goethe's poems and the works of Nietzsche—neither of which nourished much hope. But an American chaplain gave him an Army-issue New Testament and Psalms, signed by President Roosevelt. "If I make my bed in hell, behold thou art there," the prisoner read. Could God be present in that dark place? As he read on, Moltmann found words that perfectly captured his feelings of desolation. He became convinced that God "was present even behind the barbed wire—no, most of all behind the barbed wire."

Moltmann also found something new in the Psalms: hope. Walking the perimeter of the barbed wire at night for exercise, ...