SECULAR aims to analyze how society and politics in 19th century Europe are understood and explained in terms of secularized religious content. This means that modern phenomena are interpreted by reference to earlier, theological categories. The focus is on the social and political theory of the long 19th century, from 1789 to 1914: the phase from the French revolution until the outbreak of WWI, which sees the birth of modern social science as well as the rise of various ideologies. SECULAR studies the idea of secularization as a category fundamental to conceptions of social and historical reality. By centering on the triadic relationship between early socialism, the counter-enlightenment and classical sociology – with special consideration of 19th century Zionism – SECULAR offers new perspectives on how an emerging modern age imagines itself. Guiding general questions are: What is the place of secularization within modern social and political theories? How exactly can social and political facts be described as secularized religious structure? Importantly, how does the theorem of secularization influence and shape historical knowledge? This comparative approach on European ideas and their contexts, understood in the general framework of secularization theory, will offer historiographical and epistemological insights. It adds a new narrative to the entanglement of European social and political ideas. At the same time, SECULAR has a contemporary impact: Social and political theories about the relation between religion and society have a history and this history needs to be studied in order to better comprehend more recent discourses. SECULAR aims at a historical and theoretical understanding of the emergence of the idea of secularization. This understanding will explain the fragmentation, incoherence and interconnectedness of social and political theories in the larger framework of secularization as a key philosophical problem of modernity.