In AD 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 the Godhead; all other interpretations were now declared heretical. Moreover, for the first time in a thousand years of Greco-Roman civilization free thought was unambiguously suppressed. Yet su