On Friday, Pope Leo XIV will be at Lake Iznik, nearly 95 miles southeast of Istanbul. Together with some 20 Christian leaders — the list of participants has not yet been released — he will recite the Creed, the first Christian confession of faith, which was probably drafted at this very location exactly 1,700 years ago during the Council of Nicaea.
At the time, 318 bishops were convoked by Emperor Constantine to settle disputes that threatened the unity of the Church, and therefore of the empire.
Seventeen centuries later, the Christian world, representing more than 2.3 billion faithful, or nearly a third of humanity, is gathering to commemorate this first decisive ecumenical council.
A visit pending from his predecessor
Pope Francis had wanted to make this trip, but it is his successor, Pope Leo XIV, who will honor the invitation of the Ecumenical Patriarch of Constantinople, Bartholomew.
Elected head of the Catholic Church on May 8, Robert Francis Prevost does not have extensive experience in ecumenism on his resume. However, a letter published on Sunday on the occasion of his trip to Turkey shows that he intends to make Nicaea “the basis and reference point” for moving towards Christian unity. And his motto is about unity, showing that he sees the great spiritual depth of the issue.
He’s not seeking to return to the era before Christian divisions, nor to freeze them in place. Instead, he advocates for “an ecumenism that looks to the future, that seeks reconciliation through dialogue as we share our gifts and spiritual heritage.”
Desire for unity confronted with real divisions
While the prayer service at Lake Iznik will demonstrate Christian unity, it will be marked by the absence of certain Churches, notably the Patriarchate of Moscow. According to our information, the Ecumenical Patriarchate of Constantinople has decided, on behalf of the Orthodox world, to invite only the Churches of the Pentarchy.
This name refers to the ecclesiastical organization of the early centuries, with the Patriarchate of Rome for the West and the Patriarchates of Constantinople, Alexandria, Antioch, and Jerusalem for the East. Moscow would therefore not be on the guest list, although other more recent — and non-Orthodox — Churches have been invited, such as those that emerged from the Reformation.
“The Patriarchate of Moscow has broken communion with the Ecumenical Patriarchate and with that of Alexandria. This situation means that Moscow refuses to take part in initiatives led by the Ecumenical Patriarchate,” explains Archbishop Job Getcha, Metropolitan of Pisidia, whose seat is in Antalya.
Rome is watching this situation unfold. The Vatican points out that the event is taking place on the canonical territory of the Church of Constantinople, and that it is logical for the Ecumenical Patriarchate to be responsible for invitations concerning the Orthodox world.
Ukraine war has soured the Rome-Moscow relationship
But could Leo XIV's participation in this commemoration further weaken the relationship between Rome and Moscow? This relationship went through a spectacular thaw in February 2016. On that occasion, nearly a thousand years after the Great Schism of 1054, a leader of the Catholic Church met for the first time with an Orthodox Patriarch of Moscow -- the great event occurred in Cuba.
But this breakthrough, spearheaded by Pope Francis, came to a sudden halt with the invasion of Russian troops into Ukraine in February 2022, blessed by Patriarch Kirill.
Pope Francis, ever urging peace in Ukraine and even recognizing Russia's concern with NATO, nevertheless did not approve the Christian leader bowing to the Russian government.
Cardinal Koch, prefect of the dicastery for Christian Unity, described the patriarch's “pseudo-religious” justifications for the war as “heresies.” These words naturally provoked Moscow's anger.
Nevertheless, relations between Rome and Moscow are not completely at a standstill. On September 14, Metropolitan Anthony, the second-in-command of the Moscow Patriarchate, attended an ecumenical celebration dedicated to the memory of Christian martyrs in the Basilica of St. Paul Outside the Walls. In Rome, it is believed that the Nicaea commemorations will not have a major impact on relations with Moscow.
Leo XIV “has a theological clarity that appeals greatly to the Orthodox”
On another front, Pope Leo XIV may also want to reassure the Eastern Churches of his willingness to continue theological dialogue. Some observers believe that Pope Francis sometimes showed skepticism about the usefulness of this dialogue, as the Argentine was particularly attached to fraternal meetings, celebrations, and working together on issues of common importance, such as protection of life, marriage, or God's creation.
The end of Pope Francis' pontificate was also marked by turmoil in the Orthodox Church following the publication of the declaration Fiducia supplicans, authorizing blessings for those in irregular relationships, including those in same-sex relationships. While the document makes clear that it refers to a blessing for the persons, not the relationship, still, it caused widespread uproar.
In March 2024, the Coptic Orthodox Church announced the suspension of its theological dialogue with Rome. According to our information, though, this dialogue could resume in early 2026.
For Orthodox Archbishop Job Getcha, there is no break between Leo XIV and Francis.
“But in style, the new pope has a background in canon law. All his statements, homilies, and messages are measured and unequivocal. He has a theological clarity that appeals greatly to the Orthodox,” he says.
The gathering in Nicaea will therefore be Pope Leo XIV's first major ecumenical test, a way of revealing his personality and his method. The day after the commemoration at Lake Iznik, the new pope will meet behind closed doors with the leaders of the Christian churches at the Syriac Orthodox Church of Mar Ephrem in Istanbul. Each leader will be given a few minutes to speak, with no restrictive agenda.
This meeting won’t resolve the theological disputes between the Churches, nor will it lead to an agreement on the date of Easter. But the continuation of the “ecumenical synodality” inaugurated by Pope Francis could enable Pope Leo XIV to lay the foundations for a constructive relationship with his Christian brothers.
