This chapter adopts a qualitative methodology and an interdisciplinary approach drawing on literature from the sociology of religion, modernization theory and nationalism. It employs the comparative method, and more specifically the most similar systems research design, by comparing Greece and the Republic of Ireland as two similar cases which exhibit a variation in the dependent variable. Greece indeed has had the particular historical experiences that render a close relationship between religion, national identity and politics and serve as a brake on secularization. Church attendance is frequently used to measure secularization despite the obvious problems of arriving at misleading conclusions when using it as a sole indicator. In cultural defence cases, modernization confronts the Church with two sets of challenges. The first set emanates from its relationship to the state and the second from its relationship to the nation. The chapter presents an overview of this book.