The article outlines a framework for the analysis of religion and foreign policy. Despite the increased attention to religion in international relations, questions remain. Particularly controversial, yet relatively unexplored, is the role of religion in the foreign policies of states. We extrapolate from theories in the fields of international relations and comparative politics to explore religion’s potential avenues of influence on foreign policy. There are potential tools of analysis in these fields, which can be fruitfully extended and applied to understand the role of religion in foreign policy. We propose a framework within which various causal pathways and mechanisms can be situated. We also show how contributions from the field of religion and politics might be used to frame theories and specify further hypotheses about religion and foreign policy. After identifying the main threads of these lines of research, we discuss how to apply them to the question of the role of religion in foreign policy and set out a new research agenda. We conclude that the potential of these theoretical approaches to the analysis of religion has not yet been exploited.