First Ecumenical Council of the Catholic Church, held in 325 on the occasion of the heresy of Arius (Arianism). As early as 320 or 321 St. Alexander, Bishop of Alexandria, convoked a council at Alexandria at which more than one hundred bishops from Egypt and Libya anathematized Arius. The latter continued to officiate in his church and to recruit followers. Being finally driven out, he went to Palestine and from there to Nicomedia. During this time St. Alexander published his "Epistola encyclica", to which Arius replied; but henceforth it was evident that the quarrel had gone beyond the possibility of human control. Sozomen even speaks of a Council of Bithynia which addressed an encyclical to all the bishops asking them to receive the Arians into the communion of the Church. This discord, and the war which soon broke out between Constantine and Licinius, added to the disorder and partly explains the progress of the religious conflict during the years 322-3. Finally Constantine, having conquered Licinius and become sole emperor, concerned himself with the re-establishment of religious peace as well as of civil order. He addressed letters to St. Alexander and to Arius deprecating these heated controversies regarding questions of no practical importance, and advising the adversaries to agree without delay. It was evident that the emperor did not then grasp the significance of the Arian controversy. Hosius of Cordova, his counsellor in religious matters, bore the imperial letter to Alexandria, but failed in his conciliatory mission. Seeing this, the emperor, perhaps advised by Hosius, judged no remedy more apt to restore peace in the Church than the convocation of an ecumenical council.
The emperor himself, in very respectful letters, begged the bishops of every country to come promptly to Nicaea. Several bishops from outside the Roman Empire (e.g., from Persia) came to the Council. It is not historically known whether the emperor in convoking the Council acted solely in his own name or in concert with the pope; however, it is probable that Constantine and Sylvester came to an agreement (see POPE ST. SYLVESTER I). In order to expedite the assembling of the Council, the emperor placed at the disposal of the bishops the public conveyances and posts of the empire; moreover, while the Council lasted he provided abundantly for the maintenance of the members. The choice of Nicaea was favourable to the assembling of a large number of bishops. It was easily accessible to the bishops of nearly all the provinces, but especially to those of Asia, Syria, Palestine, Egypt, Greece, and Thrace. The sessions were held in the principal church, and in the central hall of the imperial palace. A large place was indeed necessary to receive such an assembly, though the exact number is not known with certainty. Eusebius speaks of more than 250 bishops, and later Arabic manuscripts raise the figure to 2000 - an evident exaggeration in which, however, it is impossible to discover the approximate total number of bishops, as well as of the priests, deacons, and acolytes, of whom it is said that a great number were also present. St. Athanasius, a member of the council speaks of 300, and in his letter "Ad Afros" he says explicitly 318. This figure is almost universally adopted, and there seems to be no good reason for rejecting it. Most of the bishops present were Greeks; among the Latins we know only Hosius of Cordova, Cecilian of Carthage, Mark of Calabria, Nicasius of Dijon, Donnus of Stridon in Pannonia, and the two Roman priests, Victor and Vincentius, representing the pope. The assembly numbered among its most famous members St. Alexander of Alexandria, Eustathius of Antioch, Macarius of Jerusalem, Eusebius of Nicomedia, Eusebius of Caesarea, and Nicholas of Myra. Some had suffered during the last persecution; others were poorly enough acquainted with Christian theology. Among the members was a young deacon, Athanasius of Alexandria, for whom this Council was to be the prelude to a life of conflict and of glory (see ST. ATHANASIUS).
The year 325 is accepted without hesitation as that of the First Council of Nicaea. There is less agreement among our early authorities as to the month and day of the opening. In order to reconcile the indications furnished by Socrates and by the Acts of the Council of Chalcedon, this date may, perhaps, be taken as 20 May, and that of the drawing up of the symbol as 19 June. It may be assumed without too great hardihood that the synod, having been convoked for 20 May, in the absence of the emperor held meetings of a less solemn character until 14 June, when after the emperor's arrival, the sessions properly so called began, the symbol being formulated on 19 June, after which various matters - the paschal controversy, etc. - were dealt with, and the sessions came to an end 25 August. The Council was opened by Constantine with the greatest solemnity. The emperor waited until all the bishops had taken their seats before making his entry. He was clad in gold and covered with precious stones in the fashion of an Oriental sovereign. A chair of gold had been made ready for him, and when he had taken his place the bishops seated themselves. After he had been addressed in a hurried allocution, the emperor made an address in Latin, expressing his will that religious peace should be re-established. He had opened the session as honorary president, and he had assisted at the subsequent sessions, but the direction of the theological discussions was abandoned, as was fitting, to the ecclesiastical leaders of the council. The actual president seems to have been Hosius of Cordova, assisted by the pope's legates, Victor and Vincentius.
The emperor began by making the bishops understand that they had a greater and better business in hand than personal quarrels and interminable recriminations. Nevertheless, he had to submit to the infliction of hearing the last words of debates which had been going on previous to his arrival. Eusebius of Caesarea and his two abbreviators, Socrates and Sozomen, as well as Rufinus and Gelasius of Cyzicus, report no details of the theological discussions. Rufinus tells us only that daily sessions were held and that Arius was often summoned before the assembly; his opinions were seriously discussed and the opposing arguments attentively considered. The majority, especially those who were confessors of the Faith, energetically declared themselves against the impious doctrines of Arius. (For the part played by the Eusebian third party, see EUSEBIUS OF NICOMEDIA. For the Creed of Eusebius, see EUSEBIUS OF CAESAREA.) St. Athanasius assures us that the activities of the Council were nowise hampered by Constantine's presence. The emperor had by this time escaped from the influence of Eusebius of Nicomedia, and was under that of Hosius, to whom, as well as to St. Athanasius, may be attributed a preponderant influence in the formulation of the symbol of the First Ecumenical Council, of which the following is a literal translation:
We believe in one God the Father Almighty, Maker of all things visible and invisible; and in one Lord Jesus Christ, the only begotten of the Father, that is, of the substance [ek tes ousias] of the Father, God of God, light of light, true God of true God, begotten not made, of the same substance with the Father [homoousion to patri], through whom all things were made both in heaven and on earth; who for us men and our salvation descended, was incarnate, and was made man, suffered and rose again the third day, ascended into heaven and cometh to judge the living and the dead. And in the Holy Ghost. Those who say: There was a time when He was not, and He was not before He was begotten; and that He was made out of nothing (ex ouk onton); or who maintain that He is of another hypostasis or another substance [than the Father], or that the Son of God is created, or mutable, or subject to change, [them] the Catholic Church anathematizes.
The adhesion was general and enthusiastic. All the bishops save five declared themselves ready to subscribe to this formula, convinced that it contained the ancient faith of the Apostolic Church. The opponents were soon reduced to two, Theonas of Marmarica and Secundus of Ptolemais, who were exiled and anathematized. Arius and his writings were also branded with anathema, his books were cast into the fire, and he was exiled to Illyria. The lists of the signers have reached us in a mutilated condition, disfigured by faults of the copyists. Nevertheless, these lists may be regarded as authentic. Their study is a problem which has been repeatedly dealt with in modern times, in Germany and England, in the critical editions of H. Gelzer, H. Hilgenfeld, and O. Contz on the one hand, and C.H. Turner on the other. The lists thus constructed give respectively 220 and 218 names. With information derived from one source or another, a list of 232 or 237 fathers known to have been present may be constructed.
Other matters dealt with by this council were the controversy as to the time of celebrating Easter and the Meletian schism. The former of these two will be found treated under EASTER CONTROVERSY; the latter under MELETIUS OF LYCOPOLIS.