With the creation of the creed, a precedent was established for subsequent 'general (ecumenical) councils of Bishops' (Synods) to create statements of belief and church law. The purpose was to define unity of beliefs for the whole of Christendom.
Constantine I called the bishops of the Christian Church to Nicaea to deal with divisions in the Church. (mosaic in Hagia Sophia, Constantinople, c. 1000)