The question as to what religion is, will remain an important and vexing issue. This book which is a translation from the original German work by Theo Sundermeier, attempts to give a theological explanation as to what religion is. In the process several important phenomenological themes are addressed, making the book relevant to a wider audience. Other topics, such as syncretism, religious tolerance and evil in religion, are also addressed. The book consists of four parts: a Phenomenological perspective, a discussion on Constitutive elements in Religion, an overview of the Encounter of Religions and a discussion on the Science of Religion as an academic subject. The book is directed at a scholarly as well as lay audience. It promises to stimulate the debate on the nature of religion.