A.D. 381: Heretics, Pagans, and the Dawn of the Monotheistic State

In A.D. 381, Theodosius, emperor of the eastern Roman empire, issued a decree in which all his subjects were required to subscribe to a belief in the Trinity of the Father, Son and Holy Spirit. This edict defined Christian orthodoxy and brought to an end a lively and wide-ranging debate about the nature of God; all other interpretations were now declared heretical. It was the first time in a thousand years of Greco-Roman civilization free thought was unambiguously suppressed.