Pope Leo XIV Calls for Christian Unity Rooted in Nicene Faith

Pope Leo XIV receives participants in the Symposium “Nicaea and the Church of the Third Millennium: Towards Catholic-Orthodox Unity.” Photo: Vatican Media

ROME — During an audience with participants of the symposium “Nicaea and the Church of the Third Millennium: Towards Catholic-Orthodox Unity,” Pope Leo XIV highlighted the enduring relevance of the First Council of Nicaea and its role in guiding modern ecumenical efforts. 

Held at the Pontifical University of Saint Thomas Aquinas in Rome from June 4 - 7, the symposium coincided with the 1,700th anniversary of the 325 AD council, which affirmed Christ’s divinity and produced the Nicene Creed.

According to reporting from Deborah Castellano Lubov of Vatican News, Pope Leo described the Council as a foundational milestone, not only historically, but spiritually – one that continues to orient the shared journey of Catholics and Orthodox Christians. 

He also recognized that the Council of Nicaea is not just one among others for Orthodox Christians, but is commemorated and celebrated in the Orthodox liturgical calendar as the “Council par excellence.”​​

Pope Leo emphasized that true unity is not the product of human planning but a divine gift, realized through the guidance of the Holy Spirit.

"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 was quoted as saying by Vatican News. “... Through theological dialogue and with God’s help, we will gain a better understanding of the mystery that unites us." 

The symposium focused on three key themes: the faith of Nicaea, synodality, and the date of Easter. The Pope reaffirmed his belief that what unites Christians – belief in the Trinity, Christ’s dual nature, baptism, resurrection, and eternal life – far outweighs remaining divisions. He also noted the Council’s establishment of synodal processes and called for greater collaboration in practicing synodality across traditions.

Touching on the longstanding calendar divide over Pascha, Pope Leo expressed hope for a shared celebration of Christ’s Resurrection, which he said would strengthen Christian witness. 

"I would reaffirm 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.

He concluded with the prayer “O Heavenly King,” a prayer to the Holy Spirit that is one of the most oft-used prayers in the Orthodox tradition, calling for the Spirit’s gift of unity to animate continued efforts toward full communion.

Previously, UOJ reported on an ecumenical prayer service held in New York to commemorate the 1,700th anniversary of the First Ecumenical Council of Nicaea.

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