This is not a book that provides a new integrated theory of religious change in modern societies, but one which develops some theoretical elements suited to make some of the contemporary religious alterations understood. Most of the approaches in sociology of religion are prone to emphasize either processes of religious decline or of religious upswing. The secularization theory, for example, might include a couple of relevant factors such as functional differentiation, economic affluence or social equality in order to account for religious change. But the result of its empirical analyses seems to be certain in advance, namely that the social relevance of religion is decreasing. In contrast, the model of the religious market devised by sociologists of religion in the U.S. is inclined to detect processes of religious upsurge everywhere. This book tries to avoid a purely theoretically guided perspective on the phenomena. That’s why it does not start with theoretical propositions but with questions which of course are theoretically framed.