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Your Holiness, Your Beatitudes, Your Eminences, Venerable Hierarchs and Clergy, Representatives of Christian Churches, Communions and Organizations throughout the world,
Brothers and sisters in Christ:
by Fr. Panagiotis Kapodistrias
In 2025, the Christian world marks 1700 years since the First Ecumenical Council of Nicaea—a defining moment in the theological formation of the Church. The Council responded to a deep need of the early Christian community: the need for a common language of faith, theological clarity, and spiritual orientation. Nicaea became a lasting point of reference for the Church of its time and for every generation seeking the truth of faith through the living experience of the Church.
By Fr. Panagiotis Kapodistrias
The Apostolic Encyclical In unitate fidei, dated 23 November 2025, was issued on the occasion of the 1700th anniversary of the First Ecumenical Council of Nicaea (325 AD). It is a theologically rich, historically grounded, and ecclesiologically oriented document. Pope Leo XIV offers more than a commemorative reflection; he presents a proposal centered on the renewal of faith in the Holy Trinity as a wellspring of life for the Church and for the modern believer.
George Florovsky
The city of Nicaea was selected as the city to host the First Ecumenical Council. Constantinople was to be officially inaugurated only in 330 and hence at the time of the convening of the Council of Nicaea the imperial residence was in Nicomedia, very close to Nicaea. Nicaea — its name comes from the Greek for “victory” — was easily accessible by sea and land from all parts of the empire. The imperial letter convening the council is no longer extant. Eusebius informs us that the emperor sent letters of invitation to the bishops of all countries and instructed them to come quickly — σπεύδειν άπανταχόθεν τους επισκόπους γράμμασι τιμητικοίς πρoκαλoυμεvoς. All expenses were to be paid from the imperial treasury. The number of bishops present has come down to us as 318 — so states Athanasius, Socrates, and Theodoret. An element of mystical symbolism became attached to this number of 318, some seeing in the Greek abbreviation a reference to the cross and a reference to the “holy name of Jesus.” St. Ambrose in his De fide (i, 18) connected the number of 318 with the number of servants of Abraham in Genesis 14:14. The number differs in other accounts. For example, Eusebius gives the number as two-hundred and fifty — πεντηκοντα και διακοσίων αριθμόν . But Eusebius does not include the number of priests and deacons. Arabic accounts from a later period give the number of more than two-thousand bishops. The extant Latin lists of signatures contain no more than two-hundred and twenty-four bishops. There appears to be no reason why the number of 318 is not in fact accurate. If one includes the number of priests, deacons, and others, then the number may have reached two thousand.