It is generally accepted that the legal doctrine of ecclesiastical public law as taught in German uni- versities in the 19th century shaped some of the basic notions of current law, particularly the core idea according to which some churches, or »reli- gious societies«, are privileged by law, whereas others are not. This system was conceived in a context where individual religious freedom and the neutrality of the state were not the leading principles, and where the objective was to create a kind of parity between the two main churches (Catholicism and Protestantism) in bi-confessional societies. The conception of a »Christian state« – that is to say, a state that always seeks to translate Christian principles in its law and in its actions and cannot, therefore, admit non-Christians among its citizens – prevailing among 19th-century scholars, and recognition extended only to Christian churches. This article studies the intellectual trans- formation of this Staatskirchenrecht shaped by Christianity into a more secularized, »public law« oriented vision. It will emphasize the essential moments of these doctrinal evolutions and their reception in positive law.