The Dicastery for Promoting Christian Unity

Four centuries of division before dialogue began

From the ruptures of the Protestant Reformation in the 16^th century and the Eastern Schism several centuries earlier, the Catholic Church had, until the mid-20^th century, no permanent structure dedicated to dialogue with separated Christians. The official position of the Holy See remained one of expecting the individual return of dissidents to the one Church of Christ, rather than a mutual search for institutional rapprochement. This position finds its clearest formulation in the encyclical Mortalium Animos of Pius XI, published on 6 January 1928 as a direct reaction to the Protestant ecumenical movement then in full expansion:

"[…] the union of Christians can only be promoted by promoting the return to the one true Church of Christ of those who are separated from it, for in the past they have unhappily left it. […]" — Pope Pius XI, encyclical Mortalium Animos, 6 January 1928^[6]

The same text warns against attempts at union founded on doctrinal compromise, which it judges to carry a precise theological risk:

"[…] for by such a course a way is easily opened to a neglect of religion or indifferentism, and to what is called Modernism." — Pope Pius XI, encyclical Mortalium Animos, 6 January 1928^[7]

In it the Pope explicitly forbids the Holy See from taking part in the "pan-Christian assemblies" then organised by the Protestant Churches and the Anglican Church, holding that to take part would amount to placing the true faith and doctrinally erroneous positions on an equal footing.

The Protestant ecumenical movement and the birth of the World Council of Churches (1948)

While Rome maintained this doctrinal reserve, an authentic movement of rapprochement had been developing since the beginning of the 20^th century between the Churches born of the Reformation and the Orthodox Churches, structured around two distinct currents: Life and Work, centred on practical social cooperation between Churches, and Faith and Order, devoted to the doctrinal questions dividing the confessions^[8]. These two currents merged on 23 August 1948 at Amsterdam to form the World Council of Churches (WCC), which from the outset brought together 147 member Churches^[9]. The Catholic Church did not join it — it is still not a member today — but Catholic theologians would take part, as observers and then as full members, in the Faith and Order commission from 1968 onwards^[10].

The Malines Conversations (1921-1925), a forgotten prelude

A notable precedent, which had no immediate institutional sequel, had nevertheless taken place a few decades earlier between Catholics and Anglicans. From 1921 to 1925, under the presidency of Cardinal Désiré-Joseph Mercier, Archbishop of Malines, Belgium hosted the Malines Conversations, the first substantial theological discussions between Catholics and Anglicans since the Reformation^[11]. Born of the friendship between the Anglican layman Lord Halifax and the French priest Fernand Portal, they brought together on the Anglican side Bishops Walter Frere and Charles Gore along with the Dean of Wells Armitage Robinson, and on the Catholic side Mercier himself, Pierre Batiffol and his successor Jozef-Ernest van Roey^[12]. Conducted with the knowledge of the Pope and of the Archbishop of Canterbury, these conversations reached a finding of partial agreement on certain doctrinal points, but Mercier's death in 1926 followed by the publication of Mortalium Animos two years later provisionally closed this path — which would only truly be reopened four decades later, with the creation of ARCIC.

John XXIII and the ecumenical intuition of the future council

Elected on 28 October 1958, Pope John XXIII announced as early as 25 January 1959 his decision to convene an ecumenical council. Among the intentions he assigned to it from the outset was concern for Christian unity: the Second Vatican Council was to become, in his wish, the occasion for the Catholic Church to engage actively in the movement of rapprochement between Christians then developing outside its fold^[13]. On 5 June 1960, by the apostolic letter Superno Dei Nutu establishing the council's preparatory commissions, John XXIII created the Secretariat for Promoting Christian Unity (Secretariatus ad Christianorum Unitatem Fovendam), the first permanent structure of the Holy See devoted exclusively to ecumenical dialogue, entrusting its presidency to Cardinal Augustin Bea^[14].

Cardinal Augustin Bea, craftsman of dialogue

Born on 28 May 1881 in Riedböhringen, Baden-Württemberg, Augustin Bea joined the Jesuits and specialised in Old Testament exegesis at the Pontifical Biblical Institute in Rome, of which he became rector in 1930, a function he held until 1949^[15]. Confessor to Pope Pius XII from 1941, he largely inspired the encyclical Divino Afflante Spiritu (1943), a decisive turning point of modern Catholic exegesis^[16]. To give Bea the authority needed for exchanges at the highest level with the other Christian Churches, John XXIII created him cardinal in December 1959, even before the official foundation of the Secretariat^[17]. Bea remained at the head of the institution until his death on 16 November 1968, having led the Secretariat through the whole of the Second Vatican Council and the first two years of the post-conciliar period.

The non-Catholic observers at Vatican II: a historic first

From its creation, the Secretariat's most visible task was to contact the non-Catholic Christian Churches and communities throughout the world in order to invite them to send observers to the council^[18]. More than a hundred delegated observers — Orthodox, Anglicans, Lutherans, Reformed, Methodists and representatives of the World Council of Churches — thus attended the council's four sessions (1962-1965), without the right to vote or to speak in the conciliar hall, but taking an active part in the informal exchanges that nourished the drafting of the texts^[19]. It was the very first time in history that a council of the Catholic Church admitted the presence of non-Catholic Christian delegates — a gesture whose symbolic importance far exceeded its protocolar framework, and which at once established the Secretariat as Rome's natural interlocutor for the non-Catholic Christian world.

Unitatis Redintegratio (21 November 1964): the charter of ecumenism

The decree Unitatis Redintegratio, prepared by Bea's Secretariat and promulgated by Paul VI on 21 November 1964 by a vote of 2,137 to 11, opens with a programmatic affirmation that makes concern for unity one of the council's own major axes:

"The restoration of unity among all Christians is one of the principal concerns of the Second Vatican Council." — Second Vatican Council, decree Unitatis Redintegratio, no. 1, 21 November 1964^[20]

The text then defines precisely what Catholic ecumenism is, and what it is not. On the one hand, it absolutely refuses any doctrinal dilution under cover of rapprochement:

"Nothing is so foreign to the spirit of ecumenism as a false irenicism, in which the purity of Catholic doctrine suffers loss and its genuine and certain meaning is clouded." — Second Vatican Council, decree Unitatis Redintegratio, no. 4, 21 November 1964^[21]

On the other hand, it places at the heart of the undertaking not theological negotiation first, but spiritual conversion and prayer:

"This change of heart and holiness of life, along with public and private prayer for the unity of Christians, should be regarded as the soul of the whole ecumenical movement, and merits the name 'spiritual ecumenism'." — Second Vatican Council, decree Unitatis Redintegratio, no. 8, 21 November 1964^[22]

It is exactly this threefold balance — complete doctrinal fidelity, the primacy of conversion and prayer, genuine openness to dialogue — that the Secretariat and then the dicastery would strive, for more than sixty years, to hold in practice before very diverse interlocutors.

Nostra Aetate (28 October 1965) and the Commission for Religious Relations with Judaism

Although devoted first to the Church's relations with non-Christian religions, the declaration Nostra Aetate, promulgated on 28 October 1965, was likewise prepared by Bea's Secretariat, because of its central chapter on relations between the Church and the Jewish people^[23]. The text rejects the thesis of a collective guilt of the Jewish people in the death of Christ and condemns every form of antisemitism — a major theological gesture that earned the declaration its reputation as the first document in Catholic history devoted specifically to the relationship with the Jews^[24]. To give concrete institutional follow-up to this text, Paul VI created on 22 October 1974, within the very Secretariat for Christian Unity, the Commission for Religious Relations with Judaism, whose first official document, published as early as 1^st December 1974, bears the title Guidelines and Suggestions for Implementing the Conciliar Declaration Nostra Aetate (No. 4)^[25]. Placed under the direction of the dicastery's prefect himself, this commission has since published three further reference documents — in 1985, in 1998 (We Remember: A Reflection on the Shoah) and in 2015, for the fiftieth anniversary of Nostra Aetate (The Gifts and the Calling of God Are Irrevocable)^[26].

Lumen Gentium and the doctrine of unity already given

The theology underlying this entire institutional effort is set by the dogmatic constitution Lumen Gentium, likewise promulgated on 21 November 1964. Its no. 8 formulates, in a sentence that has become one of the council's most commented, the conviction that the Church of Christ subsists fully in the Catholic Church while recognising, outside its visible bounds, authentic elements of sanctification:

"This Church constituted and organized in the world as a society, subsists in the Catholic Church, which is governed by the successor of Peter and by the Bishops in communion with him; nevertheless, many elements of sanctification and of truth are found outside of its visible structure. These elements, as gifts belonging to the Church of Christ, are forces impelling toward catholic unity." — Second Vatican Council, dogmatic constitution Lumen Gentium, no. 8, 21 November 1964^[27]

This formulation — the famous subsistit in — is the doctrinal bedrock on which all the dicastery's work rests: it makes it possible to recognise, among separated Christians, the real presence of elements of grace and truth (Scripture, valid baptism, a life of prayer, moral commitment), without thereby relativising the affirmation that the one Church founded by Christ subsists fully, and identifiably, in the Catholic Church governed by the successor of Peter. It is this precise balance, reaffirmed unambiguously by the Congregation for the Doctrine of the Faith in the declaration Dominus Iesus in the year 2000, that distinguishes authentic Catholic ecumenism from the relativistic indifferentism already condemned by Mortalium Animos in 1928: recognising the real good present elsewhere never amounts to denying the oneness of the Church of Christ.

1966: Paul VI confirms the Secretariat as a permanent body

With the council closed, the question arose whether to maintain the preparatory commissions created for its duration. By the motu proprio Finis Concilio of 3 January 1966, Pope Paul VI reorganised all the post-conciliar commissions and confirmed the permanence of three secretariats born in the council's orbit: the one for promoting Christian unity, the one for non-Christian religions (created on 19 May 1964 by the apostolic letter Progrediente Concilio) and the one for non-believers^[28]. The Secretariat for Christian Unity thus became, as early as 1966, a permanent body of the Roman Curia, and no longer a mere temporary conciliar structure — a status no pope has since called into question.

1988: John Paul II and the Pontifical Council for Promoting Christian Unity

By the apostolic constitution Pastor Bonus of 28 June 1988, which thoroughly refounded the organisation of the Roman Curia after the council, Pope John Paul II renamed the Secretariat the Pontifical Council for Promoting Christian Unity, without any substantial change to its competences^[29]. The same reform confirmed the attachment of the Commission for Religious Relations with Judaism to the Council, under the direct authority of its president.

2022: Praedicate Evangelium and the birth of the Dicastery

On 19 March 2022, on the solemnity of Saint Joseph, Pope Francis signed the apostolic constitution Praedicate Evangelium on the Roman Curia, the fruit of nine years of consultation of the Council of Cardinals. The text entered into force on 5 June 2022, on the solemnity of Pentecost — a date probably not indifferent for a dicastery devoted to the unity of Christ's disciples, the Holy Spirit being traditionally presented as the principle of the Church's unity. The reform renamed almost all Roman congregations and pontifical councils "dicasteries", in an explicit desire to level the Curia's internal hierarchies. The Pontifical Council for Promoting Christian Unity thus became the Dicastery for Promoting Christian Unity, its competences henceforth set out in articles 142 to 146 of the new text^[30].

A twofold mandate set by Praedicate Evangelium

Article 142 of Praedicate Evangelium sets the Dicastery's mission in a single sentence:

"It is the task of the Dicastery for Promoting Christian Unity to engage in opportune ecumenical initiatives and activities, both within the Catholic Church and in relations with other Churches and Ecclesial Communities, in order to restore unity among Christians." — Pope Francis, apostolic constitution Praedicate Evangelium, art. 142^[31]

This mandate is twofold, and it is precisely this duality that distinguishes the dicastery from most other curial institutions: it must first ensure that the ecumenical spirit pervades the internal life of the Catholic Church itself — the formation of seminarians, preaching, catechesis, liturgy — in accordance with the teaching of Unitatis Redintegratio; and it must then conduct, outwards, the effective dialogue with non-Catholic Churches and communities^[32]. The following articles of the constitution detail the concrete means of this twofold mission: seeing to the correct interpretation and faithful application of the ecumenical principles and norms established by the post-conciliar Magisterium; promoting Catholic meetings and events, national and international, favourable to Christian unity; and coordinating the ecumenical initiatives of the other institutions of the Curia and the Holy See with the other Churches and Ecclesial Communities^[33].

Appointing Catholic delegates and coordinating theological dialogues

In concrete terms, it is the Dicastery that appoints the Catholic members of all the bilateral theological dialogue commissions, as well as the Catholic observers and delegates sent to the meetings and assemblies of the other Churches and Ecclesial Communities — a practice directly inherited from the sending of observers to Vatican II, but now practised in the reverse direction^[34]. Reciprocally, whenever it seems opportune, the Dicastery invites fraternal observers or delegates of the other Churches to the most significant events in the life of the Catholic Church — synods, canonisations, great liturgical celebrations^[35]. It is also the Dicastery that prepares, each year jointly with the Faith and Order commission of the World Council of Churches, the materials for the Week of Prayer for Christian Unity, celebrated from 18 to 25 January in the northern hemisphere^[36].

The Commission for Religious Relations with Judaism today

Headed ex officio by the Dicastery's prefect, the Commission for Religious Relations with Judaism constitutes a structure in its own right within the institution, with its own secretary and its own documentary output, distinct from that of the Dicastery for Interreligious Dialogue^[37]. This architecture reflects a precise theological conviction, expressed by Nostra Aetate and developed ever since: the relationship between the Church and the Jewish people is not of the same nature as an ordinary interreligious relationship, because of the irrevocable spiritual bonds uniting the New Testament to the Old Covenant.

Two sections, Eastern and Western

Operationally, the Dicastery is organised into two major sections: an Eastern section, responsible for relations with the Orthodox Churches of Byzantine tradition, the Oriental Orthodox Churches (Coptic, Syriac, Armenian, Ethiopian) and the Assyrian Church of the East; and a Western section, responsible for dialogue with the Anglican Communion, the Churches and communities born of the Protestant Reformation (Lutherans, Reformed, Methodists, Baptists) and the World Council of Churches^[38]. Under the authority of the prefect and the secretary, the Dicastery counts one under-secretary, Msgr Andrea Palmieri^[39].

The succession of presidents and prefects since 1960

This succession — a German Jesuit, a Dutch prelate, an Australian diplomat, a German theologian and then a Swiss bishop — illustrates, as with the other great dicasteries of the Curia, the resolutely international dimension of an institution whose very vocation is to transcend confessional and national borders.

Cardinal Kurt Koch, prefect since 2010

Born on 15 March 1950 at Emmenbrücke, in the diocese of Basel, Kurt Koch studied Catholic theology at Lucerne and then Munich before being ordained a priest in 1982^[40]. A doctor of theology after a thesis on the theology of history of the Lutheran thinker Wolfhart Pannenberg — an early sign of his interest in ecumenical dialogue — he became professor of dogmatic theology at Lucerne in 1989, then Bishop of Basel on 6 December 1995^[41]. After presiding over the Swiss Bishops' Conference from 2007 to 2009, he was called by Benedict XVI in 2010 to succeed Walter Kasper at the head of the Pontifical Council for Promoting Christian Unity, and created cardinal on 20 November 2010^[42]. Fifteen years after his appointment, he remains in this post under the pontificate of Leo XIV, having led the institution through its latest statutory change in 2022 and the publication in 2024 of the document The Bishop of Rome, a major milestone of his tenure.

The Ecumenical Directory (1967, 1970, 1993)

In accordance with the wish of Unitatis Redintegratio, the Secretariat published in two stages, in 1967 and then in 1970, an Ecumenical Directory intended to translate the council decree's doctrinal principles into practical norms^[43]. This text was entirely recast and unified into a single document under the pontificate of John Paul II: approved on 25 March 1993 and presented to the press on 8 June following by Cardinal Cassidy, the Directory for the Application of Principles and Norms on Ecumenism remains today the basic normative reference for all Catholic ecumenical activity — mixed marriages, eucharistic sharing in exceptional cases, the ecumenical formation of seminarians, local pastoral cooperation^[44].

Ut Unum Sint (1995): the encyclical that opens the question of the papacy

On 25 May 1995, Saint John Paul II published Ut Unum Sint, the first encyclical in history devoted entirely to the ecumenical commitment, in which he affirmed the irreversibility of the direction taken by Vatican II in this matter. The text identifies five areas where deeper theological agreement remains necessary with the other Christian traditions: the relationship between Scripture and Tradition, the Eucharist, sacramental ordination, the pontifical Magisterium and the place of the Virgin Mary. Yet it is its no. 95, devoted to the primacy of the successor of Peter, that would have the most lasting echo in the ecumenical dialogue of the following decades:

"I ask the Holy Spirit to give us his light, and I invite all the pastors and theologians of our Churches to seek — together, of course — the forms in which this ministry may perform a service of love recognized by all concerned." — Pope John Paul II, encyclical Ut Unum Sint, no. 95, 25 May 1995^[45]

This invitation — to seek together how the primacy of the Bishop of Rome might be exercised in a manner acceptable to non-Catholic Christians, without denying anything of its proper nature — was taken up and carried forward by Benedict XVI as well as by Francis, and has for thirty years been the guiding thread of several bilateral theological dialogues, up to its most accomplished synthesis in the 2024 document The Bishop of Rome.

The Bishop and Christian Unity: the Ecumenical Vademecum (2020)

To mark jointly the 25^th anniversary of Ut Unum Sint and the 60^th anniversary of the dicastery's foundation, Cardinal Koch presented on 4 December 2020 a practical guide for diocesan bishops, entitled The Bishop and Christian Unity: An Ecumenical Vademecum^[46]. This text, requested as early as 2016 by the members of the Pontifical Council, articulates the diocesan pastor's ecumenical commitment around four complementary dimensions: spiritual ecumenism (common prayer), the dialogue of charity (a culture of encounter), the dialogue of truth (common theological research) and the dialogue of life (concrete collaboration)^[47].

Since Vatican II, the Dicastery has conducted structured theological dialogues with almost all the major non-Catholic Christian families. The following table summarises their principal normative stages:

Sources: christianunity.va, bilateral and multilateral dialogues section^[48].

Dialogue with the Orthodox: from Balamand (1993) to Ravenna (2007)

The Joint International Commission for Theological Dialogue between the Catholic Church and the Orthodox Church met for the first time in 1980, at Patmos then Rhodes. Its sixth plenary session, held on 23 June 1993 at the Notre-Dame de Balamand monastery in Lebanon, produced a document devoted specifically to the sensitive question of uniatism — that is, the attachment to Rome, in the 16^th-18^th centuries, of local Orthodox communities constituted as Eastern Catholic Churches^[49]. The statement affirms without ambiguity that this historically dated method of union can no longer serve as a model for the present search for full communion between Catholics and Orthodox, and invites both Churches to cease all reciprocal proselytism^[50]. Fourteen years later, meeting at Ravenna from 8 to 14 October 2007, the same Joint Commission published a second major document, devoted to the ecclesiological and canonical consequences of the sacramental nature of the Church: the Ravenna Document examines conciliarity and authority at the three local, regional and universal levels, and recognises that the Bishop of Rome is, historically and canonically, the protos — the first — among the patriarchs, while reserving for later work the precise study of the concrete prerogatives attached to this primacy^[51]. This dialogue continues today with the Ecumenical Patriarch Bartholomew I of Constantinople, the Holy See's principal Orthodox interlocutor since his election in 1991.

Dialogue with the Anglican Communion: ARCIC (since 1969)

Born of a meeting between Paul VI and the Archbishop of Canterbury Michael Ramsey in 1966 — four decades after the Malines Conversations — the Anglican-Roman Catholic International Commission (ARCIC) was established in 1969, after a preparatory phase that produced the Malta Report (1968)^[52]. ARCIC I (1970-1981) published statements of substantial agreement on the Eucharist (1971), the ordained ministry (1973) and authority in the Church (1976), with later clarifications in 1979 and 1981^[53]. ARCIC II (1983-2006) deepened the questions of salvation, ecclesial communion, doctrinal authority and the place of Mary in the plan of salvation^[54]. Relations nevertheless grew strongly tense around the turn of the 2000s, under the effect of women's ordinations in the Anglican Communion and then of the episcopal ordination of Gene Robinson, a non-celibate prelate living in a homosexual relationship, in 2003 — Cardinal Kasper then describing the ordination of women as a break with apostolic tradition^[55]. A third phase, ARCIC III, nevertheless opened in 2011 and continues to this day, a sign that the dialogue, though slowed on certain matters, has never been interrupted.

Dialogue with the Lutherans: justification finally reconciled (1999)

The most accomplished theological dialogue to date remains the one conducted with the Lutheran World Federation, begun as early as 1967. Signed on 31 October 1999 — the anniversary of Luther's posting of the 95 Theses — at St Anne's Church in Augsburg by the representatives of the Dicastery and the Lutheran World Federation, the Joint Declaration on the Doctrine of Justification affirms a fundamental agreement on the very article around which the conflict of the Reformation had crystallised:

"By grace alone, in faith in Christ's saving work and not because of any merit on our part, we are accepted by God […]." — Joint Declaration on the Doctrine of Justification, no. 15, 31 October 1999 (from the official English text)^[56]

The text reciprocally lifts the doctrinal condemnations pronounced in the 16^th century by the Council of Trent and by the Lutheran confessions on this precise point, without denying that real differences subsist, on other subjects, between Catholics and Lutherans^[57]. The World Methodist Council formally associated itself with it in 2006, at Seoul, followed by the World Communion of Reformed Churches in 2017, at Wittenberg; the Anglican Communion, for its part, did not formally adhere to it: its Consultative Council, meeting at Lusaka in 2016, merely "welcomes and affirms the substance" of the JDDJ (resolution 16.17)^[58]. This text remains the most accomplished example of an ecumenical resolution of a major doctrinal controversy of the Reformation^[59].

The other dialogues: Reformed, Methodists, Baptists, World Council

Beyond these three major axes, the Dicastery maintains bilateral theological dialogue commissions with the World Communion of Reformed Churches (since 1970), the World Methodist Council (since 1967), the Baptist World Alliance (conversations begun in 1984) and, more occasionally, with Pentecostal and Evangelical communities. It also takes part, via the Joint Working Group created in 1965, in permanent coordination with the World Council of Churches, without the Catholic Church thereby becoming a member — the question of Catholic membership in the WCC, regularly raised since the 1960s, has never received a positive answer from the Roman Magisterium.

Thirty years after the invitation issued by Ut Unum Sint no. 95, the Dicastery published on 13 June 2024, with the approval of Pope Francis, a substantial study document entitled The Bishop of Rome: Primacy and Synodality in Ecumenical Dialogues and in Responses to the Encyclical Ut Unum Sint^[60]. Running to more than 150 pages and 40,000 words, this text presents for the first time a systematic synthesis of thirty years of official responses received from Orthodox, Oriental, Anglican and Protestant Churches to John Paul II's invitation, as well as of the conclusions of the bilateral dialogues on primacy^[61]. It identifies several axes of possible convergence: the structural interdependence of primacy and synodality at every level of ecclesial life, the need to understand synodality as a fundamental quality of the whole Church and not as a mere procedure, and the distinction between episcopal collegiality and synodality in the broad sense^[62]. Cardinal Koch presents this document as demonstrating that pontifical primacy, far from being an irreducible obstacle to unity, can be exercised in a synodal manner — a recognised service, not an imposed sovereignty.

1,700 years of the Council of Nicaea: the joint declaration with Bartholomew I

Elected on 8 May 2025, Pope Leo XIV inherited an ecumenical dossier marked by a calendar coincidence of the first order: the year 2025 corresponds to the 1,700^th anniversary of the first ecumenical council in history, that of Nicaea (325), which fixed the Creed common to all Christians and attempted, without succeeding, to fix a common date for the celebration of Easter^[63]. On 23 November 2025, Leo XIV published on this occasion the apostolic letter In unitate fidei, before travelling to Turkey where, on 28 November 2025, he presided with Ecumenical Patriarch Bartholomew I over an ecumenical prayer at Iznik, ancient Nicaea^[64]. The next day, 29 November 2025, the two Church leaders signed a joint declaration in which they committed themselves to pursuing efforts towards a common date for the celebration of Easter between the Julian and Gregorian calendars, and jointly called on the leaders of nations to put an end to the wars in progress^[65].

Leo XIV and King Charles III: a common prayer unprecedented since the Reformation

A few weeks earlier, on 23 October 2025, Leo XIV had already made a gesture of comparable symbolic scope by receiving at the Vatican King Charles III, Supreme Governor of the Church of England, for a common prayer celebrated in the Sistine Chapel — the very first time a British monarch prayed publicly alongside a pope since the Anglican schism of the 16^th century^[66]. Centred on the protection of creation, ten years after the encyclical Laudato Si', this celebration of some thirty minutes, in English and Latin, was presided over jointly by Leo XIV and the Anglican Archbishop of York Stephen Cottrell, in the presence of prelates of both communions and with the joint accompaniment of the choirs of the Sistine Chapel and of St George's Chapel, Windsor^[67].

Leo XIV and the Archbishop of Canterbury (April 2026)

On 27 April 2026, sixty years after the historic meeting of Paul VI and Michael Ramsey in 1966, Leo XIV received at the Apostolic Palace the official visit of the Archbishop of Canterbury. Taking up the objective set in 1966 — the restoration of full communion in faith and sacramental life — the Pope affirmed there, under his episcopal motto In Illo uno unum ("In the one Christ, we are one"), echoing the words addressed by Pope Francis to the Anglican primates in 2024:

"For my part, I add that it would also be a scandal if we did not continue to work to overcome our differences, however insurmountable they may appear." — Pope Leo XIV, address to the Archbishop of Canterbury, 27 April 2026^[68]

In January 2026, on the occasion of the Week of Prayer for Christian Unity, Cardinal Koch had summed up in an interview with Vatican News the conviction that animates the Dicastery today, beyond even its own object: ecumenism as an instrument of peace for the world — the very title of the interview ("Ecumenism is a tool of peace for the world")^[69].

Neither indifferentism nor doctrinal relativism

It would be profoundly mistaken to read into this intense diplomatic and theological activity a dilution of the Catholic conviction that the Church founded by Christ subsists fully in the Catholic Church. The Catechism of the Catholic Church recalls that the unity willed by Christ for his Church is not a mere human project to be negotiated, but a gift already received to be ceaselessly deepened:

"Christ always gives his Church the gift of unity, but the Church must always pray and work to maintain, reinforce, and perfect the unity that Christ wills for her." — Catechism of the Catholic Church, § 820, citing Jn 17:21^[70]

This doctrinal precision is not a mere stylistic clause intended to reassure the Catholics most attached to tradition: it is the very condition of the credibility of ecumenical dialogue. A dialogue content merely to smooth over the real differences between Catholics, Orthodox, Anglicans and Protestants — on the Eucharist, the ordained ministry, the place of Mary, the authority of the Magisterium — would produce neither true unity nor mutual respect, but a façade agreement quickly belied by the facts: exactly the risk already denounced by Mortalium Animos in 1928. That is why every document produced by the Dicastery since 1960 — Ecumenical Directory, bilateral statements, the 2020 Vademecum, 2024's The Bishop of Rome — takes care to distinguish points of real agreement, often long negotiated and verified, from points on which disagreement remains and must be named honestly rather than masked.

A unity already given in Christ, to be brought to fullness

Authentic Catholic ecumenism, as fixed by Vatican II and as the Dicastery has striven for six decades to implement, thus rests on a two-sided conviction: on the one hand, Christians separated from Rome are never regarded as strangers to the faith, but as brothers with whom a real, though imperfect, communion already exists through baptism, the shared Scriptures and often a considerable share of sacramental and moral life; on the other hand, this imperfect communion calls of itself, in the very words of Lumen Gentium, for its own fullness in visible Catholic unity. It is this fruitful tension — between a communion already real and a fullness still to come — that the very title of the founding 1995 encyclical sums up: Ut Unum Sint, "that they may be one", the prayer of Christ himself on the eve of his Passion, and the horizon towards which the Dicastery for Promoting Christian Unity continues, a little more than six decades after its foundation by John XXIII, to lead the Catholic Church with patience.

• Dicastery for the Doctrine of the Faith — the body competent for Catholic doctrine and the authentic interpretation of the subsistit in of Lumen Gentium.
• The Dicastery for Interreligious Dialogue — the distinct body competent for relations with non-Christian religions.
• The Dicastery for the Eastern Churches — the institution competent for the Eastern Catholic Churches, in full communion with Rome.
• The Great Eastern Schism — the rupture between Rome and Constantinople at the origin of the division between Catholics and Orthodox.
• The Protestant Reformation — the 16^th-century rupture at the origin of the dialogue with Lutherans, Reformed and Anglicans.
• The Second Vatican Council (1962-1965) — the council that made ecumenism one of its major axes and founded the Secretariat for Christian Unity.
• What does the Church say about the Orthodox? — doctrinal synthesis on the relationship between Catholics and Orthodox.
• What does the Church say about Protestants? — doctrinal synthesis on the relationship between Catholics and Protestants.
• What does the Church say about Judaism? — doctrinal synthesis on the relationship between the Church and the Jewish people since Nostra Aetate.
• The Roman Curia — all the dicasteries, tribunals and offices through which the Pope governs the Catholic Church.