Pope Leo Issues Apostolic Letter on Nicaea Anniversary, Calling Church to Unity and Hope

Vatican City, November 24, 2025: Pope Leo XIV has released the Apostolic Letter In unitate fidei ahead of his upcoming Apostolic Journey to Türkiye, marking the 1700th anniversary of the First Council of Nicaea. Issued on 23 November, the Solemnity of Christ the King, the Letter is arranged into twelve points and seeks to “encourage the whole Church to renew her enthusiasm for the profession of faith.”

The Catholic Church is commemorating the Council of Nicaea, held in 325 AD under Emperor Constantine I, which addressed foundational theological disputes, affirmed Christ’s divinity, and formulated the Nicene Creed. Pope Leo’s journey will take him to Ankara, Istanbul, and Iznik—once Nicaea—the site of Christianity’s first Ecumenical Council.

Against this backdrop, Pope Leo emphasises that his Letter is, above all, a call to unity. Reflecting on the enduring profession of faith, he recalls how Christians have been called “to walk in harmony, guarding and transmitting the gift they have received with love and joy.” He highlights the words of the Creed: “I believe in one Lord Jesus Christ, the Only Begotten Son of God… for our salvation he came down from heaven,” noting that this ancient proclamation has anchored Christian identity for centuries.

The Pope stressed that the Creed “gives us hope,” calling it a common heritage that must be understood in fresh ways today. He linked this Holy Year, dedicated to Christ our hope, with the Nicaea anniversary, describing the coincidence as providential. He reaffirmed that belief in Jesus Christ, Son of God, remains “the heart of the Christian faith,” and reminded the faithful that every Sunday, Christians across the world recite this profession of unity.

Amid global conflicts, injustices, natural disasters, and widespread suffering, Pope Leo observed that the Creed continues to offer strength and direction. He emphasised that “what unites us is greater than what divides us,” commending the progress of ecumenical efforts over the last sixty years.

While acknowledging that full visible unity between the Catholic, Orthodox, Eastern Orthodox, and Reformation-born communities is still forthcoming, Pope Leo praised ecumenical dialogue grounded in shared baptism and the Nicene-Constantinopolitan Creed. This dialogue, he noted, has helped Christians “recognise the members of other Churches and ecclesial communities as our brothers and sisters in Jesus Christ.”

He highlighted that Christians share “the same faith in the one and only God,” professing together the same Lord Jesus Christ and the Holy Spirit. In a world fractured by conflict, he said, a united Christian community can become an instrument of reconciliation and peace.

Pope Leo also recalled the witness of Christian martyrs, often highlighted by Saint John Paul II, stating that their memory encourages believers to become “witnesses and peacemakers in the world.”

The Pope underscored that the Nicene Creed can serve as a reference point for the Church’s ongoing journey toward unity. He urged the faithful to leave behind outdated controversies and instead seek common understanding and prayer, guided by the Holy Spirit. True ecumenism, he said, does not erase differences but looks to the future, fostering reconciliation through shared faith and spiritual heritage.

Pope Leo concluded his Letter by inviting all Christians to pray together, invoking the Holy Spirit “to accompany and guide us in this work.”

Pope Leo Issues Apostolic Letter on Nicaea Anniversary, Calling Church to Unity and Hope

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