The spread of religions throughout the Roman world may be explained partly as a consequence of the movements of peoples, partly in terms of the emergence of new elective cults. Understanding these processes entails exploring the kinds of contacts and exchanges established between individual worshippers, and the contexts — local and imperial — within which they took place. These developments culminated in the emergence of new cults that spilled over the boundaries of the Roman Empire to create the first global religions.
* This article originated as a Conférence Michonis at the Collège de France on 5 November 2010. The original lecture (delivered in French) can be heard at http://www.college-de-france.fr/site/john-scheid/Conference_du_5_novembre_2010_.htm. I am indebted to John Scheid for the invitation, which enabled me to tackle a topic that has long been on my mind. I am grateful also to members of the audience for their questions and comments, to the Editorial Committee of the Journal, and to Mary Beard who added the finishing touches to the final version. I have also learned much from John North, Lucia Nixon and Peter Hainsworth.