I am now writing a book — Endarkenment— which traces how American politics, once built on the principles of the Enlightenment, was refashioned by evangelical Christianity—and how that faith has transformed the political left. Beginning with the Cold War bargain that brought evangelicals into Republican politics, the book follows the long arc to today’s progressive movements, which speak in a strikingly evangelical idiom: from rituals of public confession to declarations of original sin, purity tests, excommunications, apocalyptic millenarianism, and the missionary zeal to bring schools, workplaces, and institutions into their moral fold. What began as a religious turn on the right has ended as a cultural transformation on the left, leaving America with politics that looks less like a republic of citizens than a congregation of believers. This politics has estranged much of its own electorate, fueling the rise of the aggressive right and the election of Trump, with reverberations now shaking the world. The book is a call to America’s fellow citizens to wake up to this fact before it is too late.