At the 1700th anniversary of the Nicene Creed, Pope Leo XIV and Patriarch Bartholomew seek visible unity while Russia’s war has torn open deeper wounds inside Orthodoxy itself.
Newsroom (25/11/2025 Gaudium Press ) On a sun-bleached plateau in what is now northwestern Turkey, the emperors and bishops of the fourth century once argued, prayed, and finally hammered out the Nicene Creed, the closest thing Christianity has to a universal profession of faith. Seventeen centuries later, Pope Leo XIV will stand on the same ground beside Ecumenical Patriarch Bartholomew I to mark that moment, reciting together the words that still bind most of the world’s Christians.
In a new apostolic letter released Sunday, In Unitate Fidei, the pope framed the anniversary not merely as commemoration but as a summons. After recalling the “bitterly divisive doctrinal disputes” that both preceded and followed 325, Leo observed that global Christianity is now largely united on the essential nature of the Trinity. “We must therefore leave behind theological controversies that have lost their raison d’être,” he wrote, “in order to develop a common understanding and, even more, a common prayer to the Holy Spirit, so that he may gather us all together in one faith and one love.”
The phrase echoes a conviction shared by every pope since Vatican II: “truly, what unites us is much greater than what divides us.” Yet the pope’s own journey to Nicea will unfold against a backdrop far more tangled than the optimistic rhetoric might suggest.
The centerpiece of the visit will be the joint prayer service with Bartholomew, the primus inter pares of global Orthodoxy and, for three decades, Catholicism’s most steadfast partner in the search for full communion. The two men will stand before the ruins of the ancient basilica where Constantine once presided and recite the Creed in its original form, without the Filioque clause that became one of the formal triggers of the Great Schism of 1054.
Their personal rapport is genuine. Bartholomew has exchanged gifts, messages, and visits with every pope from John Paul II onward. In 2020 Pope Francis told him, “Although obstacles remain, I am confident that by walking together in mutual love and pursuing theological dialogue, we will reach that goal.” Asked the same year by The Pillar whether full communion was realistic, the patriarch replied simply: “Dialogue and reconciliation are not optional for us; they are directives and commandments.”
Quiet but substantive progress has continued. In 2023 a joint Catholic-Orthodox theological commission produced the first new agreed document in years, on synodality and primacy, declaring that “the interdependence of synodality and primacy is a fundamental principle in the life of the Church.” Last year Francis revived the ancient papal title “Patriarch of the West,” a move quietly welcomed in some Eastern circles as a gesture of genuine synodality rather than universal jurisdiction.
Yet the most formidable obstacle to Leo’s vision is no longer the millennium-old breach between Rome and Constantinople. It is the breach inside Orthodoxy itself, dramatically widened by Russia’s invasion of Ukraine.
The Russian Orthodox Church, by far the largest Eastern Church, has tied its ecclesiastical claim to primacy among the Orthodox to explicit theological endorsement of Vladimir Putin’s war, which its leaders have repeatedly called a “holy war.” Moscow has simultaneously sought to suppress the independent Ukrainian Orthodoxy, prompting Bartholomew and most of the world’s autocephalous Churches to recognize the Orthodox Church of Ukraine as fully autonomous in 2019. Moscow responded by declaring a complete break in communion with Constantinople and several other patriarchates.
The result is the most serious schism within global Orthodoxy since 1054, and it has direct consequences for Catholic-Orthodox rapprochement. On one side, Moscow and its allies have long been the most implacable opponents of closer ties with Rome; their self-imposed isolation from many ecumenical forums has paradoxically removed some of the loudest anti-Catholic voices from the table. On the other side, any visible warming between Rome and Constantinople now risks being perceived, in Moscow and beyond, as taking sides in an inter-Orthodox civil war.
Bartholomew is acutely aware of the danger. In a second interview with The Pillar last year he insisted that Catholic-Orthodox agreements “in no way should create more tension among our Churches and especially among the various local Orthodox Churches.” He has continued to pray publicly for “the healing of the 1054 schism” while calling the war in Ukraine “diabolic.”
Pope Leo’s letter appears calibrated to that delicate reality. He speaks of walking together toward “unity and reconciliation among all Christians,” with the Nicene Creed as “the basis and reference point,” offering “a model of true unity in legitimate diversity.” The phrase “legitimate diversity” is deliberately spacious, yet it is precisely there that the hardest questions remain.
For Rome and Constantinople the remaining doctrinal differences, especially over papal primacy, are serious but no longer appear insoluble to many theologians on both sides. The more immediate question may be whether Orthodoxy itself can agree on where legitimate diversity ends and unacceptable division begins.
When Leo and Bartholomew pray the Creed together in Nicaea, they will do so as leaders of communities that, taken together, comprise the overwhelming majority of the world’s non-Protestant Christians. Whether that moment becomes a milestone toward full communion or merely another poignant gesture of fraternal closeness will depend less on what happens on the ancient shoreline and more on whether the Orthodox world can heal its own wounds, and whether Rome can find a way to encourage that healing without appearing to exploit it.
Seventeen hundred years ago, an emperor and several hundred quarreling bishops managed, against steep odds, to say the same thing about the nature of God. The leaders gathering in Niceae this year carry a heavier burden: to show that Christians can still say the same thing about the nature of the Church.
- Raju Hasmukh with files from The Pillar
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