Sometimes the stone that the builders rejected ends up as the cornerstone of the whole building.  That may not quite describe the role of Christianity in American foreign policy, but in some important and little understood ways the massive surge of Christian faith in the developing world is tilting the global playing field in America's favor.  At home, the appeal and the vigor of African-American Christianity, especially of the Pentecostal variety, may be America's best defense against a sharp increase in home-grown terror. From Barbary to Baghdad Managing the impact of Christianity at home and abroad on...