What happens to American democracy if Christianity is no longer able, or no longer willing, to perform the functions on which our constitutional order depends? In his provocative new book, Cross Purposes, the award-winning journalist Jonathan Rauch reckons candidly with both the shortcomings of secularism and the corrosion of Christianity. Thin Christianity, as Rauch calls the mainline church, has been unable to inspire and retain believers. Worse, a Church of Fear has distorted white evangelicalism in ways that violate the tenets of both Jesus and James Madison. What to do?