The central idea behind this book is that the globalisation and politicisation of traditional religious identities is a historical phenomenon with deep roots in the 19th-20th centuries. Tracing the emergence of 'Religious Internationals' as a distinctive new phenomenon in world history, it transforms our understanding of the place of religion in the modern world. Leading historians and social scientists break new ground by comparing the historical experiences of different faith communities in an age of globalization without comparing them as religions. In-depth case studies focus on the internationalist dimensions of Buddhism, Christianity (Catholic, Orthodox, Protestant), Hinduism, Judaism and Islam. Individually, they illuminate the complex processes whereby communities of believers became communities of opinion. Collectively, they shed new light on the origins and nature of global civil society, highlighting the role of religion as one of its motor forces from the start.