We're not going to stop any presses by declaring that Christianity has suffered serious decline in Europe—the place where apostles preached, and where Aquinas, Calvin, Luther, Barth, and countless other spiritual luminaries called home. Witness, to take just one example, the current sad turmoil in the Anglican Communion between the theological liberals of the statistically stagnant British mother church and their conservative brethren in rapidly growing, vibrant African and Asian dioceses.

Until recently, many Western academics accepted the sociologists' "secularization thesis," which asserts that intellectual advance and economic modernization lead people and nations past a need for faith, to a more enlightened and more secular mode of life. Europe's ongoing and increasing contempt for organized religion has been their prime example, while the growth of Christianity in countries such as Nigeria and China have been dismissed as a primitive stop on the road toward a godless society.

Perhaps no nation more proudly flaunts its secularism than France. The land that launched the millennium of Christendom by crowning Charlemagne Holy Roman Emperor in 800 has morphed into a staunchly secularist state, opposed to even the most cursory mention of Christianity's historic influence in the European Union's recently drafted constitution. Over the years France has exemplified the convergence of academic skepticism and popular unrest that has produced empty church pews across the continent.

But events have thrown the secularization thesis into disrepute—to the point where few now defend it in its original form. At the crux of this intellectual shift is one piece of glaring counter-evidence: the United States of America. American Christianity ...