Religious ideas have been largely absent in the literature on the welfare state. Instead, class-interest based, rational efficiency, and institutional explanations have dominated. The absence of religious ideas is not a peculiarity of welfare state research but is paralleled by a treatment of ideas as ephemeral to politics in general. The introductory chapter reviews the literature on ideas and politics and the literature on the influence of ideas on welfare policy in particular. It shows why ideas could not play a role in the welfare state literature till today and proposes a solution: to integrate ideas into the study of welfare state evolution. The chapter creates an analytical framework for the study of evolving religious ideas and their impact on welfare state formation and reform in Italy and Germany. It engages with the weaknesses and strengths of both welfare state theory and the new ideational turn literature and introduces a theory of ideational competition. The chapter concludes with a short descriptive outline of the book and the following chapters.