Nazi Germany produced an unusual group of Christian martyrs--among them, the nun philosopher Edith Stein, the mystical philosopher Simone Weil, and the peasant conscientious objector Hans JSgerstatter--but perhaps none so complex as the Lutheran theologian Dietrich Bonhoeffer. Born into a large upper-middle-class, professional family that was not particularly devout or observant (his father was one of the leading psychiatrists in Germany), Dietrich...