The September 11, 2001 terrorist attacks on the United States brought the issue of terrorism to the forefront of American attention and controversy. To determine how to prevent further destruction, it is necessary to understand the shadowy phenomenon that causes it. Who are the terrorists? What are their motives? What are the roots of this form of violence, and will it come to an end? What exactly is terrorism?

Ami Pedahzur and Arie Perliger, world experts on the study of terror and security, propose a theory of violence that contextualizes not only recent acts of terror but also instances of terrorism that stretch back centuries. Beginning with ancient Palestine and its encounters with Jewish terrorism, the authors analyze the social, political, and cultural factors that sponsor extreme violence, proving religious terrorism is not the fault of one faith, but flourishes within any counterculture that adheres to a totalistic ideology.

When a totalistic community perceives an external threat, the...