In Godless Democrats and Pious Republicans?, Ryan Claassen challenges the conventional wisdom that the Republican Party has been “captured” by activists from the Religious Right, leading to a backlash that has driven seculars to the Democratic side. This “God Gap” thesis suggests that the two American political parties are divided with the religious Republicans on one side and the non-religious Democrats on the other. Claassen argues that rather than indicating a drastic over-representation of power within the party, the rise of evangelical activists in the Republican Party and secular activists in the Democratic Party reflects demographic changes in society. Drawing on American National Election Studies (ANES) data from 1960–2008 to examine changes over time, Claassen identifies four forces that have altered the religious makeup of the parties' activist pools: (1) changes in the population size of religious groups; (2) changes in voter turnout rates of religious groups; (3) changes in party loyalty of religious groups; and (4) changes in campaign activism in religious groups. After carefully deriving the modeling approach that is used to test his representation-based theory, Claassen devotes chapters 4–7 to examining each of the four forces in turn.

Of these phenomena, it is the demographic shifts that provide the most explanatory power. In identifying these demographic changes and carefully formulating models to demonstrate their effects on the composition of the parties' activist pools, the book makes a significant contribution. The finding that most of the changes in the makeup of the parties' electoral coalitions and activist pools can be explained by the population growth of evangelicals and seculars — rather than primarily by mobilization from the Christian Right or Secular Left — is a new and important insight. Put simply, it is not that evangelicals or seculars outhustled everyone else in mobilization, but rather that their numbers in the general population and in the partisan electorates have grown at higher rates. Claassen shows in chapters 5 and 6 that apparent increases in turnout and partisan loyalty among evangelicals and seculars dissipate once socio-economic status is controlled. Further, he demonstrates that changes in loyalty rates cause changes in levels of activism — not the other way around. This provides more support for Claassen's representation-based model, and it casts doubt on the applicability of the issue evolution model that has been prominent in the literature on partisan change.

Another powerful blow is landed against the God Gap thesis when Claassen compares southern and non-southern evangelicals. The evangelicals outside the south did not show a trend of increased support for Republicans, unlike those in the south. Southern evangelicals were significantly more conservative on racial issues but did not differ from non-southern evangelicals on abortion, suggesting that the God Gap account has misidentified morality politics as the primary impetus for realignment. Claassen summarizes the point as follows: “… the rise of morality politics and greater Republican loyalty among Evangelicals are incidental to a broader realignment around issues of race” (161).

Throughout the book, the careful data analysis is well documented in the text and appendices, and is presented clearly in tables and numerous graphical figures. The book is a great model of how to effectively mine the ANES data series, and scholars seeking to replicate and extend Claassen's findings will appreciate the thorough documentation of the techniques used. The more technical aspects of the model-building are sectioned off in such a way that readers who are less mathematically inclined can bypass these derivations and move into the descriptive prose, making the book more accessible for students.

When an author sets out to debunk a conventional wisdom, he or she can expect to encounter the criticism that a straw man has been set up and then, unsurprisingly, knocked down. Claassen will likely face that charge in some quarters with respect to his characterization of the God Gap view of party “capture” by activists. There is no doubt that many journalistic accounts have adopted the facile view that the Republican Party was overtaken by hordes of religious conservatives, which led to the secular-dominated Democratic Party waging a counterattack in the “war on religion.” But it is less clear how many scholars of religion and politics ever fully embraced the capture-and-backlash view that Claassen ably dismantles. Similarly, some readers will question the use of church attendance as the measure of religious traditionalism. It is true that some simple versions of the God Gap account have relied solely on attendance, but more nuanced analyses would go beyond this single measure of religious practice to include doctrinal measures such as views of the Bible. However, what Claassen does with the church attendance variable is done well, and he demonstrates the weakness of a simplistic God Gap account in which church attendance is always a force for political conservatism.

Claassen's book stays focused on the task of refuting the party capture thesis, but the analysis raises many interesting questions for future exploration. What has led to the generational changes in religious affiliation (and disaffiliation) that Claassen documents? What should we make of the growth of religious “nones” over this time period? Does it make sense to treat all the unaffiliated as a monolithic “secular” category in our analyses? Why is the Religious Left not more visible and successful? And thinking more broadly about the book's potential impact, how might Claassen's representation-based modeling approach apply beyond the study of parties and religion in America? Are their applications to social groups other than religious ones? Might the approach travel outside the United States to the study of parties elsewhere in the world? I expect that researchers will build upon the solid foundation laid down by Claassen's work to address these and other questions in future studies. Godless Democrats and Pious Republicans? is an important book that deserves to be read closely by scholars of religion and politics, parties, and voting behavior.