Constantine called the First Council of Nicaea in 325 to unify Christology , also called the first great Christian council by Jerome , the first ecumenical , decreed the Original Nicene Creed , but rejected by Nontrinitarianism such as Arius , Theonas , Secundus , Eusebius of Nicomedia , and Theognis who were excommunicated , also addressed Easter controversy and passed 20 Canon laws . Constantine called the First Council of Nicaea in 325 to unify Christology , also called the first great Christian council by Jerome , the first ecumenical , decreed the Original Nicene Creed , but rejected by Nontrinitarians such as Arius , Theonas , Secundus of Ptolemais , Eusebius of Nicomedia , and Theognis of Nicaea who were excommunicated , also addressed Easter controversy and passed 20 Canon laws such as Canon VII which granted special recognition to Jerusalem .