Offering the first comprehensive, interdisciplinary account of what Christian nationalism in America is and isn't, and how it became the political religion of Donald Trump's MAGA movement, the essays in this book describe the way Christian nationalism has embedded itself in American politics. Understanding Christian Nationalism emphasizes that Christian nationalism's sacralization of the US must be seen against the backdrop of American civil religion, which since the founding of the republic has represented the country in sacred terms that transcend political partisanship. By contrast, partisanship is central to the Christian nationalist enterprise. Although Christian nationalist politics can be found in the 19th century, the book shows that the Christian nationalism experienced in today's America derives from the rise of the religious right in the late 1970s. Adapting civil religious language to advance the electoral success of the Republican Party, the religious right set the stage for the MAGA movement by promoting the restoration of a country dominated by White, heterosexual men, when Protestant Christianity enjoyed favored status as the country's effective religious establishment. The collection makes clear that the use of religious language to characterize the US is not exclusively an expression of Christian nationalism. It also demonstrates that many Christian nationalists in America see themselves as part of an international movement to restore Christian values around the world. Featuring essays that use historical methods, media analysis, survey data, interview and ethnographic observations, this book is essential to students, instructors, and readers in sociology, social theory, sociology of religion, cultural sociology, US history, and politics to understand the Christian nationalism integral to Trump's appeal and electoral success.