This introduction presents an overview of the key concepts covered in the subsequent chapters of this book. The book was itself both an outcome of and a complement to the European Science Foundation Transformation of the Roman World research project in which Mayke de Jong had been a leading spirit. It deals with religious discourse and political polemic in studies that take up the themes of identity, and the creative deployment of the language of the Old Testament within Frankish society. The book explores early medieval uses of the biblical metaphor of a 'chosen people' in the early Middle Ages. It also explores how the use of ethnic rhetoric in a Christian context shaped medieval perceptions of community. The book further considers the implications of the invocation of the Emperor Constantine in the debates about Adoptionism at the end of the eighth century.