The twentieth century has seen no phrase so consistently popular with Protestant America as "What Would Jesus Do?" What began as a series of evening story-sermons delivered by a Kansas preacher in 1896 became by the end of the century a billion dollar industry as millions of Americans purchased bracelets, t-shirts, coffee mugs, and other paraphernalia with the acronym "WWJD?" inscribed upon them. For some the remarkable sales which the phrase engendered bespoke a hunger for the Christian gospel in the American public sphere, but to others it showcased the ability of market-savvy capitalists to turn even the deepest religious impulses into profit-making ventures.

Charles M. Sheldon (1857-1946), a social gospel minister at the Central Congregational Church in Topeka, Kansas, landed on the idea of the story-sermon as a cure for chronically poor attendance at Sunday evening services. These serial messages...