As the Church marks the 30th anniversary of Ut unum sint, St. John Paul II’s landmark encyclical on Christian unity, Church leaders and theologians are once again drawing attention to its enduring importance — especially in an era still marked by division, war, and a longing for reconciliation among Christians, and in the context of the 1,700th anniversary of the Council of Nicaea.
Signed on May 25, 1995, by John Paul II, Ut unum sint (“That they may all be one”) was the first papal encyclical dedicated entirely to ecumenism. It formally reaffirmed the Catholic Church’s irreversible commitment to seeking unity among Christians, in line with the vision of the Second Vatican Council’s Unitatis redintegratio, and according to Jesus' prayer at the Last Supper, found in John 17:20-23:
“I ask not only on behalf of these but also on behalf of those who believe in me through their word, that they may all be one. As you, Father, are in me and I am in you, may they also be in us, so that the world may believe that you have sent me. The glory that you have given me I have given them, so that they may be one, as we are one, I in them and you in me, that they may become completely one, so that the world may know that you have sent me and have loved them even as you have loved me.
In Christopher Wells’ article for Vatican News, Deacon Daniel Galadza, professor at the Pontifical Oriental Institute in Rome, said “Ut unum sint built on the Council’s work and gave it new momentum […] It didn’t just encourage dialogue; it placed the pursuit of Christian unity at the heart of the Church’s mission.”
The document addressed not only theological questions but also the spiritual and moral urgency of unity. Drawing from Christ’s prayer in the Gospel of John — “that they may all be one” (Jn 17:21) — it acknowledged the pain of centuries-old divisions and invited separated Christian communities, particularly the Orthodox churches, into deeper communion.
One of the encyclical’s most significant contributions was its emphasis on the Eastern Christian tradition. Pope John Paul II spoke of the Church “breathing with both lungs” — East and West — and referred to the Orthodox as “sister Churches,” a term that underscored shared apostolic roots and sacramental life.
From John Paul II to Leo XIV
These themes have taken on renewed relevance in 2025, a jubilee year in the Catholic Church and the first of Pope Leo XIV’s pontificate. Shortly after his election, Pope Leo held a long-planned audience with leaders and faithful of the Eastern Catholic Churches — a gesture many interpreted as an implicit ecumenical message to all Eastern Christians.
“Even if the Pope didn’t speak directly about ecumenism, he was speaking to all of them,” says Deacon Galadza, who attended the gathering. “The Eastern Catholic Churches have a vocation to work for unity, and that vocation echoes the spirit of Ut unum sint.”
In the decades since the encyclical’s publication, there have been many signs of progress.
Yet challenges remain. Theological disagreements over papal primacy, the Filioque clause, and intercommunion persist. But for many, Ut unum sint provides a framework for continued dialogue — not as a call for uniformity, but for communion rooted in mutual respect, truth, and charity.
As the Church commemorates this anniversary, the encyclical stands as both a prophetic witness and a practical roadmap. For a Church longing to heal wounds across centuries and continents, the vision of Ut unum sint — and the hope it carries — remains as vital now as it was thirty years ago.
