The 9/11 terrorist attacks had a grave impact on the way the conflict dynamics in world politics have been shaped, structured and interpreted since then. To fight or prevent international terrorism still appears as a top-priority for the great powers of the West and questions about the role of religion in explaining the motivations and occurrences of terrorist acts still remain topical. Today, more than ten years after the events of 9/11, the discipline of IR is still struggling with theoretical and methodological puzzles about how to study and conceptualize the religion-violence nexus. As the contributions in this Forum display, the conceptual and methodological debate is important because of its implications for conventional IR thinking on key issues such as the legitimacy of violence and war, the question of what decides human behavior and what leads to human conflict. The contributions attempt to bring more transparency into the religion-violence debate.