What is the ideology supporting the concept that a society's ruler is God's direct representative on earth to administer justice and punish evil doers?

Theocracy, the dumbest form of government ever devised. It is a back door way to say Dictatorship since there is no god handing down the rules, only some guy that claims he gets his direction from god. That way when something goes wrong all he has to say is "god made me do it"; what a load.