Book excerpt: Why do white Protestants in America embrace a president who seems to violate their basic standards of morality? The answer, Andrew Whitehead and Samuel Perry argue, is "Christian nationalism," the belief that the United States is -- and should be -- a Christian nation. Knowing someone's stance on Christian nationalism, this book shows, tells us more about his or her political beliefs than race, religion, or political party. Drawing on national survey data and interviews with Americans across the political spectrum, Taking America Back for God illustrates the tremendous influence of Christian nationalism on debates about the most contentious issues dominating American public life.