"Christendom" refers to a society where Christianity is essentially compulsory. Western Europe, however, has been gradually moving away from Christendom for more than two centuries towards a society where a great variety of religious and non-religious options are available and none is able to claim a privileged position. Written by historians, sociologists and theologians from six countries, and including chapters on most European countries, this study examines this process of increasing pluralism and its implication for the future.