NUNTIATORIA

Ecumenism without Conversion: Leo XIV and the Illusion of Unity

Pope Leo XIV, addressing participants of 2025’s Ecumenical Week, drew striking parallels between the First Ecumenical Council of Nicaea (325) and the 1925 Lutheran-led Ecumenical Conference in Stockholm. In his address, the pope referred to Catholics and Protestants as “fellow disciples of Christ,” declaring that “what unites us is far greater than what divides us.”

“Since the Second Vatican Council, the Catholic Church has wholeheartedly embraced the ecumenical path,” Leo affirmed, casting his message as a continuation of the post-conciliar programme of dialogue and rapprochement. He extolled Archbishop Nathan Söderblom, the Lutheran primate of Uppsala and pioneer of the early ecumenical movement, who urged Christians to unite not in doctrine but in “practical Christianity.”

Such rhetoric, however, marks a profound departure from the perennial Catholic position. Pope Pius XI, in his encyclical Mortalium Animos (1928), issued an unambiguous prohibition: “The Apostolic See cannot on any terms take part in their assemblies, nor is it anyway lawful for Catholics either to support or to work for such enterprises; for if they do so they will be giving countenance to a false Christianity, quite alien to the one Church of Christ.”¹

Pius XI insisted that true unity could only be secured “by promoting the return to the one true Church of Christ of those who are separated from it.”² By contrast, Leo XIV echoed the theological turn inaugurated at Vatican II, where Unitatis Redintegratio (1964) redefined unity as a gradual convergence through dialogue, worship “where possible,” and “shared witness.”³

The pope hailed ecumenical milestones such as John Paul II’s visit to Uppsala and Francis’s participation in the 2016 Reformation commemoration in Lund. Francis went so far as to praise Martin Luther’s emphasis on Scripture and justification, even describing his theological revolt as a “medicine for the Church.”⁴ Leo now builds upon this trajectory, proposing that the “unity signalled by Nicaea” finds a modern analogue in Söderblom’s Stockholm Conference.

But the comparison falters on every essential point. Nicaea defined the Creed and anathematised Arius, drawing lines of orthodoxy that preserved the Catholic faith.⁵ Stockholm, by contrast, explicitly set aside doctrine in favour of vague “practical Christianity,” affirming division rather than resolving it. To invoke Nicaea in such a context risks trivialising the very substance of Catholic unity: one faith, one baptism, one Church.

Traditional voices have raised the alarm. “If the Eucharist, papal primacy, Marian dogmas, and moral law are mere ‘divisions,’ then unity is reduced to vague good feelings,” noted Catholic commentator Chris Jackson, warning that ecumenism has become “an end in itself, a theology of horizontal fraternity in which truth is relativised.”⁶

Leo has also signalled his willingness to “tone down” papal primacy in order to placate Orthodox and Protestant interlocutors, cautioning against “vying for greatness” among the Sees. This diminishment of Rome’s divine prerogatives runs counter to Vatican I’s dogmatic teaching on the papacy, which defined the primacy of Peter’s successor as de fide: “If anyone thus speaks, that the Roman Pontiff has merely an office of inspection or direction, but not full and supreme power of jurisdiction over the whole Church… let him be anathema.”⁷

The deeper concern is not fraternity but faith. The early popes and councils laboured to preserve unity by safeguarding the deposit of truth, condemning error and recalling the wayward to the fold. Today’s ecumenism, severed from the necessity of conversion, risks exchanging truth for sentiment. As Pius XI warned nearly a century ago, such endeavours “foster a false Christianity, quite alien to the one Church of Christ.”⁸

The Old Roman Position
For the Old Roman Apostolate, the issue is clear. Christian unity cannot be founded upon compromise, nor upon the erasure of Catholic dogma in favour of broad fraternity. The Faith handed down from the Apostles requires both integrity and clarity. To speak of Protestants and Orthodox as “sister churches” or “fellow disciples” without conversion is to obscure the very nature of the Church as una, sancta, catholica et apostolica.

We recognise, with sorrow, that the modern Vatican has traded the supernatural mission of the Church for ecumenical diplomacy. As with the Society of St. Pius X, our position is not one of schism but of fidelity: we resist these novelties in the name of the Faith that cannot change. True unity remains possible—but only by the return of separated brethren to the one true fold of Christ, not by constructing a new ecclesial edifice of pluralism.

The lesson of Nicaea was not accommodation but clarity: the Creed, the anathemas, and the Church’s unwavering defence of divine truth. If Stockholm symbolised a turning to human compromise, then the task of faithful Catholics today is to turn back to the faith of the Fathers. 🔝

¹ Pius XI, Mortalium Animos (6 January 1928), §8.
² Ibid., §10.
³ Vatican II, Unitatis Redintegratio (21 November 1964), §4.
⁴ Pope Francis, Address at Joint Lutheran–Catholic Commemoration of the Reformation, Lund (31 October 2016).
⁵ Council of Nicaea I, Symbolum Nicaenum (325).
⁶ Chris Jackson, “Pope Leo XIV and the Stockholm Ecumenical Week,” Substack Commentary (2025).
⁷ Vatican I, Pastor Aeternus (18 July 1870), Chapter 3, Canon 3.
⁸ Pius XI, Mortalium Animos, §8.