Pope Leo XIV addressed Catholic and Orthodox participants this morning, June 7, at a symposium in Rome on the Council of Nicea and the journey to Christian unity. His talk focused on three key topics: the faith of Nicea, synodality and the date of Easter.
Speaking off script, he apologized for arriving “a bit late,” thanked participants for their patience, and said, “I am not yet one month into the new job, so there are a lot of learning experiences. But I am very happy to be with you this morning.”
The symposium, “Nicaea and the Church of the Third Millennium: Towards Catholic-Orthodox Unity,” was jointly organized by Œcumenicum—the Institute for Ecumenical Studies of the Angelicum (formally known as the Pontifical University of St. Thomas Aquinas, where Pope Leo studied canon law)—and the International Orthodox Theological Association.
Cardinal Kurt Koch, the Swiss-born prefect of the Dicastery for the Promotion of Christian Unity, and the members of that Vatican office were present at the gathering, at which Pope Leo greeted representatives of the Orthodox and Oriental Orthodox Churches, “many of whom,” he said, “honored me by their presence at the Mass inaugurating my pontificate.”
The inaugural Mass took place on May 18, and the Ecumenical Patriarch Bartholomew of Constantinople, first among equals in the leadership of the Orthodox churches, was present. The patriarch had a private audience with Pope Leo on May 19 and spoke about it that evening, ANSA reported, when he told TG2000, the Italian Catholic television channel, “I saw with great satisfaction that we can continue on the same path as our churches for all of Christianity, for peace in the world.” He added that Pope Leo “assured me that he wants to come to Turkey for the anniversary of Nicaea. We have not set a concrete date, but certainly this year. Maybe Nov. 30.”
In his talk this morning, Pope Leo said he was pleased to see that the symposium “is resolutely oriented toward the future” because “The Council of Nicaea is not merely an event of the past but a compass that must continue to guide us towards the full visible unity of Christians.” He emphasized that the council, which took place in 325 CE, “is foundational for the common journey that Catholics and Orthodox have undertaken together since the Second Vatican Council.”
He noted, moreover, that for the Eastern churches “the Council of Nicaea is not simply one council among others or the first in a series, but the council par excellence, which promulgated the norm of the Christian faith, the confession of faith of the ‘318 Fathers.’”
Pope Leo recalled the International Theological Commission’sDocument for the 1700th anniversary of Nicaea, issued on April 3. In that document, the commission noted that the year 2025 represents “an invaluable opportunity to emphasise that what we have in common is much stronger, quantitatively and qualitatively, than what divides us.” It highlighted the fact that “together, we believe in the Triune God, in Christ as truly human and truly God, and in salvation through Jesus Christ, according to the Scriptures read in the Church and under the guidance of the Holy Spirit. Together, we believe in the Church, baptism, the resurrection of the dead, and eternal life.”
Leo told his ecumenical audience: “I am convinced that by returning to the Council of Nicaea and drawing together from this common source, we will be able to see in a different light the points that still separate us.” He explained that “through theological dialogue and with the help of God, we will gain a better understanding of the mystery that unites us.”
“By celebrating together this Nicene faith and by proclaiming it together, we will also advance towards the restoration of full communion among us,” he said.
The American pope next drew attention to synodality. It is something that he is personally committed to as he made clear in his first address to the world from the central balcony of St. Peter’s Basilica on the night of his election as pope.
“The Council of Nicaea inaugurated a synodal path for the Church to follow in dealing with theological and canonical questions at the universal level,” he said, adding that “the contribution of the fraternal delegates from the Churches and ecclesial communities of East and West to the recent Synod on Synodality held here in the Vatican was a valuable stimulus to greater reflection on the nature and practice of synodality.”
Pope Leo knows this well because, as a cardinal, he had attended both the 2023 and 2024 sessions of the synod and listened to their input. In his talk today, he recalled that the synod’s final document noted that “ecumenical dialogue is fundamental for developing our understanding of synodality and the unity of the Church” and it went on to encourage the development of “ecumenical synodal practices, including forms of consultation and discernment on questions of shared and urgent interest.”
“It is my hope that the preparation and joint commemoration of the 1700th anniversary of the Council of Nicaea will be a providential occasion, as that final document said, ‘to deepen and confess together our faith in Christ and to put into practice forms of synodality among Christians of all traditions,’” he told his ecumenical audience.
One of the objectives of the Council of Nicaea, Pope Leo recalled, was to demonstrate the unity of the church by establishing a common date for Easter throughout the world.
“Sadly, differences in their calendars no longer allow Christians to celebrate together the most important feast of the liturgical year, causing pastoral problems within communities, dividing families and weakening the credibility of our witness to the Gospel,” he said.
He noted, however, that “several concrete solutions have been proposed that, while respecting the principle of Nicaea, would allow Christians to celebrate together the ‘Feast of Feasts,’” as they did this year.
The missionary pope, like Pope Francis, reaffirmed “the openness of the Catholic Church to the pursuit of an ecumenical solution favouring a common celebration of the Lord’s resurrection and thus giving greater missionary force to our preaching of ‘the name of Jesus and the salvation born of faith in the saving truth of the Gospel,’” he said quoting from his speech last month to the Pontifical Mission Societies.
He concluded his talk by reminding his ecumenical audience that “the unity for which Christians long will not be primarily the fruit of our own efforts, nor will it be realized through any preconceived model or blueprint. Rather, unity will be a gift received ‘as Christ wills and by the means that he wills’ (Prayer for Unity of Father Paul Couturier), by the working of the Holy Spirit.” He invited all present to stand and join him in reciting a prayer from the Eastern tradition:
O Heavenly King, the Comforter, the Spirit of Truth,
Who art everywhere and fillest all things;
Treasury of Blessings, and Giver of Life,
Come and abide in us, and cleanse us from every impurity,
and save our souls, O Good One.
Amen.
Pope Leo then imparted his blessing and greeted each of them.
