This book tackles key questions that bedevil scholars of contemporary terrorism: Why is religious terrorism on the rise today? Why are religious terrorists so deadly? What accounts for the different patterns of success and failure among different terrorist groups? Why have we seen a shift toward the use of suicide terrorism among religious terrorists? And, what is to be done to counter the menace of religious terrorism? Eschewing more traditional explanations that depict the behavior of religious terrorists as motivated by individual psychosis, myths of spiritual reward in the afterlife, or the dehumanization or “otherness” of victims that are part and parcel of religious conflicts, Eli Berman makes use of a rational actor framework in which radical religious communities are better at motivating and maintaining the loyalty of their members. The result is an arresting and highly readable book—he uses simple descriptive statistics and qualitative case studies in the main text and appends sophisticated economic charts—that will be of interest to scholars and students of terrorism in multiple disciplines.

Berman's definition of “radical” religious groups is surprising at first—any nonmainstream religious community, violent or otherwise, whose conditions of membership require significant sacrifice and serve to isolate members from the larger society—but it is crucial to the main argument of the book. Put simply, for the author, religious radicals are better at solving group collective-action problems. If terrorist groups are to be resilient and effective in launching attacks, they must prevent individual defection, that is, informing, divulging secrets, failing to execute orders, or leaving the group entirely. Using economic theory, he traces out the scenarios under which terrorist group members might opt to defect, and how detrimental this is to the effectiveness of the group as a whole, and then employs a novel qualitative discussion of examples of successful contemporary terrorist movements, such as Hamas, Hezbollah, the Afghan Taliban, and the Iraq-based Shi'i Mahdi Army, contrasting them with less successful terrorist groups, such as the Jewish underground, whose plot to bomb the Jerusalem al-Aqsa mosque was uncovered by Israeli intelligence with the help of a group defector.

According to Berman, what separates successful groups with high-defection constraints from unsuccessful, low-defection constraint groups are the internal incentives of group membership. In the book, he argues that all radical religious communities function as economic “clubs” that require considerable sacrifice from members as a condition of entry and isolate their members from mainstream economic communities. These high membership costs help to guarantee the commitment and loyalty of members more efficiently, thereby raising the defection constraint, by creating pools of “club goods” that members become highly dependent on, and these costs serve as a means for controling the behavior and commanding the loyalty of members.

Berman explains the value of sacrifice and dependence on club goods by exploring, as one example, the unusually rapid growth and political influence of ultra-Orthodox Jewish communities in Israel from the 1970s to the present day. To become a member of an ultra-Orthodox community, one must forgo much more lucrative mainstream educational and job opportunities in order to study at religious schools (Yeshivas) full time for many years. This impoverishes members, but the community also provides substantial mutual aid, offering sustenance in times of need while fostering loyalty, facilitating collective action—in the case of Israel, ultra-Orthodox blocks of voters have become politically potent—and instilling a sense of separation from the outside society.

The author makes an arresting, though perhaps to some readers uncomfortable, comparison of the ultra-Orthodox in Israel with the Hamas terrorist organization. Hamas was created in the 1980s as the armed wing of the Palestinian Muslim Brotherhood, a social movement known at the time mostly for the extensive social services it provided to Muslims in the West Bank and Gaza. He attributes the meteoric rise of Hamas—from an obscure movement that prior to 1987 often called strikes in the occupied territories that Palestinians ignored to a formidable armed movement that was able to militarily wrest de facto control of Gaza from Fatah in 2007—to its ability to prevent its cadres from joining other movements or from collaborating with the Israelis. Indeed, Berman notes that Hamas pioneered and successfully utilized suicide terrorism in Israel and the Palestinian territories, a tactic that requires enormous defection constraints from perpetrators.

How specifically do successful—and, by extension, more dangerous—terrorist groups overcome defection? Berman puts forth six methods. They demand serious and permanent financial and social sacrifice from initiates. They use their nonviolent social services wings as vast recruiting pools for higher-quality cadres. They use the selective benefits derived from their social service wings to manipulate and enforce loyalty among experienced cadres in the movement, while attacking rival social services, such as those provided by government or relief agencies. They can use streams of revenue, derived from taxation, extortion, state subsidy, smuggling, and so on, to enhance community benefits and further increase their leverage over group members. They use their stocks of violent capacity to dominate local politics and political institutions, weakening the state and political rivals. Finally, they isolate their members socially from larger societies, both increasing loyalty and facilitating, Berman thinks, acts of extraordinary violence and cruelty against outsiders.

These core elements also lead Berman to his main counterterrorism recommendation: Officials should “outcompete” terrorist movements in providing social benefits. Effective counterterrorism should make defection, via leaving the group and cooperating with officials, more lucrative for terrorists. His discussion of successful rehabilitation programs of republican and loyalist prisoners and of Yassir Arafat's program to “retire” violent Black September cadres in the 1970s as the Palestine Liberation Organization was angling for observer status at the United Nations are among the most arresting anecdotes in the book. In both cases, terrorists were offered a second chance at a normal life, with stable jobs, housing, and reconnection with family, friends, and loved ones outside of the movement. This part of Berman's argument has important implications for the burgeoning literature on poverty and terrorism and buttresses work by Brian Burgoon (“On Welfare and Terror,” Journal of Conflict Resolution 50 [April 2006]: 176–203), who finds that states that provide more extensive welfare benefits experience less terrorism.

Radical, Religious and Violent is not, however, without its shortcomings. Perhaps the most important of these is that it is difficult to see how religion, specifically, fits into the mainstay of Berman's argument. One can imagine that strong religious conviction might make individuals join radical religious communities, or terrorist groups, in the first place, but this is not really developed in the book. Many secular terrorist movements similarly provide club goods to members and seek to isolate them from mainstream society. A related and more important shortcoming is that his analysis really cannot explain the prominence, and effectiveness, of Al Qaeda–type groups, which are “successful” if frequent attacks and high casualties—Berman's metrics—are markers of success. In fairness, he notes this but offers little in the way of explanation and refrains from making what would be the natural argument: that Al Qaeda's failure to reduce defection through provision of selective benefits will make it a less effective movement in the future vis-à-vis, for example, the Pakistani Taliban. Finally, some scholars will quibble with Berman's assumption that Hamas-provided social benefits, such as widow and orphan aid, sports and scouting clubs, and medical clinics, are truly selective rather than universal benefits.

On balance, however, the book is interesting and generates many testable hypotheses. It serves to inject economic theory into the study of terrorism and terrorist groups dynamics, a field often accused of undertheorization. It furthermore is well written and stands to serve scholars of terrorism and students alike.