Caesaropapism is the idea of combining the power of secular government with the religious power, or making it superior to, the spiritual authority of the Church; especially concerning the connection of the Church with government. The term caesaropapism (Cäseropapismus) was coined by Max Weber, who defined it as follows: “a secular, caesaropapist ruler... exercises supreme authority in ecclesiastic matters by virtue of his autonomous legitimacy”. According to Weber's political sociology, caesaropapism entails “the complete subordination of priests to secular power.”
In its extreme form, caesaropapism is a political theory in which the head of state, notably the Emperor ('Caesar', by extension an 'equal' King), is also the supreme head of the church ('papa', pope or analogous religious leader). In this form, it inverts theocracy (or hierocracy in Weber) in which institutions of the Church control the state. However, both Caesaropapism and theocracy are systems in which there is no Separation of Church and State and the two form parts of a single power structure.