On Friday, Pope Leo XIV joined patriarchs and priests from both the Eastern and Western branches of Christianity to honor a significant milestone in Christian history. The gathering took place in Turkey at the historic site of the A.D. 325 assembly of bishops, where they prayed for the unity of Christians worldwide.

Alongside Ecumenical Patriarch Bartholomew I and other prominent Christian figures, Leo convened on the banks of Lake Iznik. This location is renowned as the venue of the Council of Nicaea, which established a creed that continues to be a cornerstone of faith for millions across the globe.

Amidst the ancient ruins, the leaders recited this creed, underscoring its crucial role in the ongoing journey toward unity among Christians. Leo emphasized its significance, stating, “It is essential in our shared path towards complete communion.”

He further remarked, “We are urged to transcend the divisions that persist as a scandal and to foster the yearning for unity that Jesus prayed for and sacrificed his life for.”

This prayer service was the focal point of Leo’s visit to Turkey, marking the primary purpose of his inaugural trip as Pope.

Religious leaders lead an Ecumenical prayer service near the archaeological excavations of the ancient Basilica of Saint Neophytos in Iznik, Turkey, on Nov. 28, 2025. (AP Photo/Domenico Stinellis)

A crucial moment in Christianity

The Nicaea gathering took place at a time when the Eastern and Western churches were still united. They split in the Great Schism of 1054, a divide precipitated largely by disagreements over the primacy of the pope. But even today, Catholic, Orthodox and most historic Protestant groups accept the Nicaean Creed, making it a point of agreement and the most widely accepted creed in Christendom.

As a result, celebrating its origins at the site of its creation with the spiritual leaders of the Catholic and Orthodox churches and other Christian representatives marked a historic moment in the centuries-old quest to reunite all Christians. 

“The Nicene Creed acts like a seed for the whole of our Christian existence. It is a symbol not of a bare minimum; it is a symbol of the whole,” said Bartholomew, spiritual leader of the world’s Orthodox Christians.

At the start of the prayer service, he told the men they were gathering not just to remember the past. 

“We are here to bear living witness to the same faith expressed by the fathers of Nicaea. We return to this wellspring of the Christian faith in order to move forward,” he said.

A prayer for unity

Roman Emperor Constantine had convened the gathering of bishops from around the Roman Empire after he had consolidated control following years of civil war and political intrigues.

Constantine wouldn’t formally convert to Christianity until the end of his life, in 337. But by 325, he had already been showing tolerance and favor toward a Christian sect that had emerged from the last great spasm of Roman persecution.

The version of the creed that emerged from the council, and recited today by Catholics, begins: “I believe in one God, the Father almighty … “

The service commemoration, which featured alternating Catholic and Orthodox hymns, took place at the lakeside archaeological excavations of the ancient Basilica of Saint Neophytos. The stone foundations of the basilica, which were recently uncovered by the lake’s receding waters, are believed to be on the site of an earlier church that hosted the council 1,700 years ago.

Senior clerics attend an outdoor religious ceremony in Turkey on Nov. 28, 2025. (AP Photo/Domenico Stinellis)

In addition to Leo and Bartholomew, the participants of the commemorative service included priests, patriarchs and bishops from Orthodox Greek, Syrian, Coptic, Malankarese, Armenian, Protestant and Anglican churches. 

In his remarks to the men, Leo said all Christians must strongly reject the use of religion to justify war, violence “or any form of fundamentalism or fanaticism.”

“Instead, the paths to follow are those of fraternal encounter, dialogue and cooperation,” he said.

A brief protest before Leo arrived

Christians are a minority in predominantly Sunni Muslim Turkey, and ahead of the prayer in Iznik, around 20 members of a small Turkish Islamic party staged a brief protest. They said the encounter posed a threat to Turkey’s sovereignty and national identity. 

Under a heavy police presence, Mehmet Kaygusuz, a member of the New Welfare Party, read a statement denouncing what he said were efforts to establish a “Vatican-like Greek Orthodox state” in Turkey. The group dispersed peacefully shortly after.

Iznik resident Suleyman Bulut, 35, acknowledged his town’s deep historical and spiritual significance for Christians and said he had no issue with them coming to honor their heritage. 

“Muslims (too) should go and visit places that belong to us in the rest of the world, in Europe,” he said.

But Hasan Maral, a 41-year-old shopkeeper, said he felt uncomfortable with the visit. “The pope coming here feels contradictory to my faith,” he said.

A boost for Turkey’s tiny Catholic community

Leo began his first full day in Istanbul by encouraging Turkey’s tiny Catholic community to find strength in their small numbers. According to Vatican statistics, Catholics number around 33,000 in a nation of 85 million, most of whom are Sunni Muslims.

He received a raucous welcome at the Cathedral of the Holy Spirit, where he was greeted with shouts of “Papa Leo” and “Viva il Papa” (Long Live the pope).

“The logic of littleness is the church’s true strength,” Leo told them in English. “The significant presence of migrants and refugees in this country presents the church with the challenge of welcoming and serving some of the most vulnerable.”

Clerics walk in a religious procession during an ecumenical prayer service in Iznik, Turkey, on Nov. 28, 2025. (AP Photo/Domenico Stinellis)

Leo later visited with a group of nuns, the Little Sisters of the Poor, who run a nursing home in Istanbul.

“He was so simple. We just felt he was at home. He felt very much at ease. Everybody got what they expected: a blessing, a kind word. It’s just enormous,” said Sister Margret of the Little Sisters of the Poor Nursing Home.

On Saturday, Leo continues with his ecumenical focus, meeting with Bartholomew and other Christian leaders. But he’ll also visit the Sultan Ahmed Mosque, commonly known as the Blue Mosque, and will celebrate a late afternoon Mass in Istanbul’s Volkswagen Arena.

Leo heads to Lebanon on Sunday for the second and final leg of his trip.

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