Minecraft wiki entry for Building_a_metropolis, associated text: Theocracy
A form of government in which a god or deity is recognized as the state's supreme civil ruler. Since said god or deity is usually absent from decision making, a self-appointed or elected leader or leaders of the religion of said god or deity will rule instead through the personal interpretation of the laws commanded by the god in that religion's written law.
You could use real gods or deities, or make up your own! (Example: make the citizens believe in the religion of Apollo, or the religion of Intreksino).