Caesaropapism /ˌsiːzəroʊˈpeɪpɪzəm/ is the idea of combining the social and political power of secular government with religious power, or of making secular authority superior to the spiritual authority of the Church; especially concerning the connection of the Church with government. Although Justus Henning Böhmer (1674–1749) may have originally coined the term caesaropapism (Cäseropapismus), it was Max Weber (1864–1920) who wrote that "a secular, caesaropapist ruler... exercises supreme authority in ecclesiastic matters by virtue of his autonomous legitimacy." According to Weber, caesaropapism entails "the complete subordination of priests to secular power."
In an extreme form, caesaropapism is where the head of state, notably the emperor ("Caesar", by extension a "superior" king), is also the supreme head of the church (pope or analogous religious leader). In this form, caesaropapism inverts theocracy (or hierocracy in Weber), in which institutions of the church control the state. Both caesaropapism and theocracy are systems in which there is no separation of church and state and in which the two form parts of a single power-structure.
Weber's formal definition of caesaropapism in Economy and Society reads as follows: 'a secular, caesaropapist ruler... exercises supreme authority in ecclesiastic matters by virtue of his autonomous legitimacy.
Caesaropapism entails 'the complete subordination of priests to secular power,' and it essentially means that church matters have become part of political administration ... .