The premise of the book is quite simple, signaled clearly by the subtitle—“Blocked Ambition and the Paths to Jihad.” On its face, the premise seems plausible. Limiting access to a desired outcome serves to drive goods or people outside the system. In the case Nielsen presents, state control of the plum positions Muslim clerics can hold creates resentment. Those driven outside of state institutions turn to extremist theologies/ideologies, but also because extremist theologies are popular. Other work has linked state regulation of religion to extremism and violence, of course, but the strength of Nielsen's book is the work he does to document the mechanisms involved in this simple claim. His project takes us into teaching mosques, through social networks, pouring over academic cleric CVs, searching religion on the internet, and coding fatwas, uniting ethnographic methods with big text-as-data applications in powerful ways.

It is a “crisis of authority” in the Islamic world that allows this analysis to take place. Nielsen starts chapter 2 with a conversation that is surely curious to scholars: “Who counts as a cleric?” There is no single accepted definition, there are no credentialing bodies, and there are a wide variety of roles clerics may play. Nielsen decides to focus on people who produce religious content, which is of course convenient for someone looking to code text and credentials. But a behavioral definition has the benefit of being empirically verifiable and also skirts the politics at the heart of the project. If jihadists were defined out of the clergy as illegitimate, there would be no research question.

Since there are no “official” clergy, this leaves open the question of credibility, which clerics are invested in demonstrating. In part because of their academic training, recognizable norms have developed and several core indicators are used to display credibility on Facebook and Wikipedia pages, among other sources, including listing teachers, positions, relatives, jail time, and relatives, among other symbols on their CVs. Moreover, clerics gain status and followers from their writings, which are widely available on the web.

The book proceeds in what turns out to be a primer on using text data, causal inference, and data visualization. It answers the questions: Who are (prominent) clerics available online? How can we confidently code writing for jihadism? What proportion of clerics are jihadist? How does jihadism correlate with scholar network size and outsider status? Is preaching jihadism popular? The answers to many of those questions build toward a test of blocked ambition in Chapter 5 from both quantitative and qualitative approaches. To motivate you to read the book, I will simply summarize that he finds support for his theory, but also that it is not the dominant process linking clerics and jihadism.

I will also say that I am impressed with the nuance and care with which Nielsen approaches this subject. It seems like it would be easy to doggedly push a strong theoretical orientation, but that is not what we read here. While Nielsen is looking for evidence to evaluate a political economy approach to religion, he makes the point that theology is important and may work hand in hand with social structural influences. A considerable effort went in to looking for blocked ambition, but Nielsen makes every effort to look for alternate explanations. It is exemplary social science.

But I still wish, selfishly, that this was a book addressing religion and politics theory. Since Nielsen wrote this for scholars of Middle East and North Africa, comparative scholars of radicalism, and others, the book addresses very little applicable religion and politics work (save for a nice paragraph on pp. 14–15). So, I will spare a few words to write some of the applications and connections to work on clergy and radical religion. Nielsen is right to connect this work to scholars working from the political economy of religion perspective. In this view, political regulation (or the lack thereof in the United States, for instance) drives particular configurations of the religious market.

Considering supply and demand characteristics allows us to search for instances in which religion bends to the interests of potential followers. This is a shift in perspective from most of what has come before. That is, there is quite a bit of literature that finds clergy theological viewpoints are closely related to their political commitments and behavior (see Pastors and Public Life: The Changing Face of American Protestant Clergy, New York, 2016 for a review). Essentially none of the work on clergy in the modern era considers circumstances akin to what Nielsen's clerics-in-training faced; instead they survey senior, denominational clergy in a pulpit at one point in time. Therefore, this remains an open question for researchers (or those who look back to the civil rights era). But there is some research that has examined how clergy behave in what might be relabeled frustrating circumstances and the answer is a similar one—they seek to preserve their position through multiple mechanisms. Some shift their reference groups to support their desired behavior (e.g., to denominational officials––“Choosing Constituent Cues: Reference Group Influence on Clergy Political Speech,” Social Science Quarterly vol. 90, no. 1). Clergy diversify their public speech when facing disagreement to appease various factions (e.g., “The Deliberative Pulpit: The Democratic Norms and Practices of the PCUSA,” Journal for the Scientific Study of Religion vol. 51, no. 1); and some facing disagreement tend to convey individualist (“fairness”) values which could reinforce congregant tolerance for the clergy's diverse views (“Moralizing to the Choir: The Moral Foundations of American Clergy,” Social Science Quarterly vol. 99, no. 2). Of course, the old finding that religious activists during the Civil Rights movement were more likely to come from positions that insulate them from retribution fit this scheme as well (“Authority and Controversial Policy: The Churches and Civil Rights,” American Sociological Review vol. 35, no. 6).

This is to say that a general theory of religious actors in politics may be in sight. It is too strong to say that clergy are wholly endogenous to their social and political contexts, but it is reasonable to conclude that clergy are highly constrained by their environments, which under some circumstances may drive their ministries in unintended, but predictable directions.

This is an important book for those who care about explaining the political behavior of religious actors, but it is also important for those making policy recommendations about the regulation of religion around the world, which has been resurging a bit over the last decade (see e.g., An Introduction to Religion and Politics: Theory and Practice, New York, 2013). Moreover, I recommend it for anyone thinking about using text as data and for anyone who could benefit from seeing a problem worked with extraordinary care.