Today, religion is a complex issue. In Western Europe, the so-called ›Christian heritage‹ is challenged by both other religious traditions and secular worldviews. It is therefore essential to understand the complexity of religion in different contexts. This volume addresses four questions in this regard: How can we assess religion and religiosity appropriately? What are important markers of religiosity? How does religion affect recent society? How can religion be taught in modern society? By dealing with these questions, the contributions to this volume offer an insight into the state-of-the-art of research on religion and religiosity within the field of religious education on an international level.