 Most notably , from 313 to 316 bishops in North Africa struggled with other Christian bishops who had been ordained by Donatus in opposition to Caecilian . The African bishops could not come to terms and the Donatists asked Constantine to act as a judge in the dispute . Three regional Church councils and another trial before Constantine all ruled against Donatus and the Donatism movement in North Africa . In 317 Constantine issued an edict to confiscate Donatist church property and to send Donatist clergy into exile . More significantly , in 325 he summoned the Council of Nicaea , effectively the first Ecumenical Council ( unless the Council of Jerusalem is so classified ) . The Council of Nicaea is most known for its dealing with Arianism and for instituting the Nicene Creed . 
