In The Age of Evangelicalism: America's Born-Again Years, Steven P. Miller examines the emergence of the evangelical group as a political and cultural force in America during the 1970s through its decline in the early 2010s. Miller's survey narrative is brief but touches on many different aspects of history, political science, cultural analysis, and historiography. His approach is not one that ties into the core beliefs of evangelicals or incorporates a theological perspective but rather a more outsider approach that feels objective and perhaps a tad secular. It would require a lot more than 163 pages of text to present an overview of evangelical beliefs as they are more diverse than contemporary discourse suggests. This is where the historiographical sections of the book excel as Miller proficiently illustrates how the "Age" was one of right, moderate, and left leaning viewpoints. This explains the acceptance of Carter's born-again rhetoric, the Christian realignment under Reagan, the moderate perspectives of Clinton, Bush's compassionate conservatism, and Obama's adoption of moderate evangelical perspectives.
At its heart, this is a political history told from a top down viewpoint through the lenses of presidents, church leaders, Christian intellectuals, and authors. The cultural aspects of Miller's analysis are sprinkled in for good measure. More of these details would have added a lot to the work and also about religion in the late 20th Century. However, the moderate tone and sharp prose of the author make this an accessible read for those who are outside the community and wish to grasp Christianity's role in contemporary politics. While the history of evangelicalism can be viewed as its own entity with different categories of historiography, The Age of Evangelicalism also fits into late 20th Century studies like Bruce Schulman's The Seventies and Daniel T Rogers' The Age of Fracture. All of these studies illustrate the ebb and flow of Christianity throughout the 70s, 80s, and 90s while describing an overall turn to the Right in America.
For a comprehensive context of political Christianity during the 20th Century, I would recommend reading this after One Nation Under God by Kevin Kruse.