Religious rivalry exists where groups of people distinguish themselves from others on the basis of differing beliefs and practices touching identity and life's meaning. These differences were addressed in a variety of ways, depending on levels of tolerance: ranging from violence, which captures most attention, through polemic and debate to compromise and negotiation. While all sought to resolve rivalry, the means chosen could involve either an escalation or de-escalation of the conflict. In the early centuries of its existence, Christianity reacted both to internal differences between members and to external differences with non-Christians. In fresh case studies, the essays in this volume examine not only patterns of escalation of rivalry but also emphasise strategies adopted that sought to de-escalate tensions.