The terrorist attacks of 9/11—in which al-Qaeda operatives flew airplanes into the World Trade Center and the Pentagon and attempted to crash an additional plane into the Capitol Building in Washington, DC—highlighted for many the role religion could play in terrorism. Al-Qaeda, an Islamist terrorist network striving to undermine U.S. influence in Muslim countries, combined a global religious ideology with brutal violence in a way that caught the attention of policymakers and scholars. Since then, academics have been attempting to analyze and understand how religion and terrorism intersect. Scholars have debated whether religion is a distinctive aspect of contemporary terrorism or is secondary in importance to other factors, such as nationalism and rational calculations. Some scholars take a critical approach to the topic, pointing to normative concerns with the study of religion and terrorism, and disparate other scholars have analyzed how religion and terrorism relate to a vast array of topics from public opinion to political repression. After surveying the literature, it is difficult to question the distinctiveness of religious terrorism. Yet it also appears that terrorism does not arise inevitably from religious beliefs, nor is it unique to Islam. Moreover, religion seems to be connected to the transnational nature of contemporary terrorism. One particularly useful approach moving forward may be to draw on the relational approach to contentious politics that scholars such as Charles Tilly have formulated. This article’s approaches religious terrorism as violence or the threat of violence motivated by religion that intends to effect political change. This article will thus focus on how acts of violence that fall within the above definition relate to “religious imperatives,” and what the effects of these connections are. Charles Tilly’s approach to political violence, which conceptualizes terrorism as one manifestation of the range of political violence types, extends from brawls and riots to full-scale civil war. As a result, insights into how religion affects related forms of political violence can inform our understanding of religion and terrorism. Terrorism can also be understood as a nonstate phenomenon. Although states can commit terroristic acts, terrorism as a distinct tactic involves nonstate actors. State behavior—particularly religious repression—can have significant impact on the incidence and severity of religious terrorism in a country, however.