This comprehensive Handbook examines relationships between religion and international relations, mainly focusing on several world religions - Christianity, Islam, Hinduism and Judaism. Providing a timely update on this understudied topic, it evaluates how this complex relationship has evolved over the last four decades, looking at a variety of political contexts, regions and countries. Original chapters analyse how varying religions shape people’s attitudes towards the organisation and operations of political systems worldwide. As well as investigating core issues and topics such as religion, foreign policy, terrorism and international security, the Handbook also provides clarity on topical and controversial issues such as Islamist extremism, Hindu nationalism and Christian civilisationism. Top international contributors offer further analysis via important case studies of religion and international relations across the globe. Providing crucial information, this Handbook will be an excellent resource for higher-level students and researchers of religious studies, international relations and politics, as well as policy makers and professionals from a variety of backgrounds and orientations.