20th.May 325 The First Council of Nicea.

• 325 – The First Council of Nicea – the first Ecumenical Council of the Christian Church is held.
• Overview
  The First Council of Nicaea was the first ecumenical council of the Church. Most significantly, it resulted in the first, uniform Christian doctrine, called the Nicene Creed. With the creation of the creed, a precedent was established for subsequent local and regional councils of Bishops (Synods) to create statements of belief and canons of doctrinal orthodoxy—the intent being to define unity of beliefs for the whole of Christendom.

  One purpose of the council was to resolve disagreements arising from within the Church of Alexandria over the nature of the Son in his relationship to the Father: in particular, whether the Son had been 'begotten' by the Father from his own being, or rather, created out of nothing, a characteristic shared with other creatures. St. Alexander of Alexandria and Athanasius took the first position; the popular presbyterArius, from whom the term Arianism comes, took the second. The council decided against the Arians overwhelmingly (of the estimated 250–318 attendees, all but two agreed to sign the creed and these two, along with Arius, were banished to Illyria).

  Another result of the council was an agreement on when to celebrateEaster, the most important feast of the ecclesiastical calendar, decreed in an epistle to the Church of Alexandria in which is simply stated:

  We also send you the good news of the settlement concerning the holy pasch, namely that in answer to your prayers this question also has been resolved. All the brethren in the East who have hitherto followed the Jewish practice will henceforth observe the custom of the Romans and of yourselves and of all of us who from ancient times have kept Easter together with you. 

   Historically significant as the first effort to attain consensus in the church through an assembly representing all of Christendom, the Council was the first occasion where the technical aspects of Christology were discussed. Through it a precedent was set for subsequent general councils to adopt creeds and canons. This council is generally considered the beginning of the period of the First seven Ecumenical Councils in the History of Christianity.

  Character and purpose

  

  

  Constantine the Great summoned the bishops of the Christian Church to Nicaea to address divisions in the Church (mosaic inHagia Sophia, Constantinople (Istanbul), ca. 1000).

  The First Council of Nicaea was convened by Emperor Constantine the Great on the recommendations of a synod led by Hosius of Córdoba in the Eastertide of 325. This synod had been charged with investigation of the trouble brought about by the Arian controversy in the Greek-speaking east. To most bishops, the teachings of Arius were heretical and dangerous to the salvation of souls. n the summer of 325, the bishops of all provinces were summoned to Nicaea, a place reasonably accessible to many delegates, particularly those of Asia Minor,Georgia, Armenia, Syria, Palestine, Egypt, Greece, and Thrace.

  This was the first general council in the history of the Church since the ApostolicCouncil of Jerusalem, the Apostolic council having established the conditions upon which Gentiles could join the Church.  In the Council of Nicaea, "The Church had taken her first great step to define revealed doctrine more precisely in response to a challenge from a heretical theology."