The Holy See
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(Rocca di Papa, MONDO MIGLIORE, 11,12 and 13 November 2004)


Rocca di Papa (Mondo Migliore)
Thursday, 11 November 2004

Lasting significance and urgency
of Unitatis redintegratio


The Decree on Ecumenism –
Read Anew After Forty Years

On 21 November 1964 the Decree on Ecumenism Unitatis redintegratio (UR) was solemnly proclaimed by the Second Vatican Council. Already in the introduction we find the statement: “Christ the Lord founded one church and one church only; division openly contradicts the will of Christ, scandalises the world and damages the holy cause of preaching the Gospel”. “The restoration of unity among all Christians is one of the principal concerns of the Sacred Ecumenical Second Vatican Council.”

Forty years have passed since that day, and the influence exerted by this document in that time constitutes an incomparable record. Forty years represent a Biblical time-span, so we have good grounds for asking: What was the intention of this document? What effect has it had, and where do we stand today in regard to ecumenism? What is the future direction of ecumenism? Quo vadis ecumenism?

The Council is the Magna Charta for the pathway of the church into the 21st century (Tertio millennio adveniente, 18). The Pope has repeatedly said that the path of ecumenism is irreversible (Ut unum sint [UUS] 3 and passim); ecumenism is one of the pastoral priorities of his pontificate (UUS, 99). So the question arises: What are the Catholic principles of ecumenism as formulated by the Decree Unitatis redintegratio?

I. The development of the Decree on Ecumenism

The Decree on Ecumenism did not fall readymade from heaven. It forms a part of the ecumenical movement which had arisen outside of the Catholic Church during the 20th century (UR, 1, 4) and which achieved a decisive breakthrough with the formation of the World Council of Churches in 1948. This movement was for a long time regarded with suspicion by the Catholic Church. But its reception by the Second Vatican Council has roots reaching back to the Catholic theology of the 19th century. Johann Adam Möhler and John Henry Newman in particular should be mentioned as forerunners and pioneers.

The way was also prepared by the Holy See. Even prior to the Second Vatican Council the Popes fostered the Prayer for Unity and the Week of Prayer for Unity. Popes Leo XIII and Benedict XV prepared the way for openness towards ecumenism; Pope Pius XI gave express approval of the Malines Conversations with the Anglicans (1921-1926).[2]

Pope Pius XII went a step further. In an Instruction of 1950 he expressly welcomed the ecumenical movement and attributed it to the influence of the Holy Spirit. In addition, this Pope also paved the way for the Council with a series of groundbreaking encyclicals. It would therefore be erroneous to overlook this fundamental continuity and see the Council as a radical breach with tradition and the advent of a new church.


II. Ecumenism – Expression of the Eschatological Dynamic of the Church

But something new did in fact begin with the Council, not a new church but a renewed church. It was Pope John XXIII who initiated this renewal. He can rightly be called the spiritual father of the Decree on Ecumenism. He wanted the Council, and he set its goals: the renewal inside the Catholic Church and the unity of Christians.

It is not my intention to outline here the eventful history of the genesis of Unitatis redintegratio as it overturned the narrow post-Tridentine Counter-Reformation outlook of the church.[3] This was not “Modernism”, rather it was a return to the Biblical, patristic and early-medieval tradition, opening the way for a renewed understanding of the church.

The Council was able to embrace the ecumenical movement because it understood the church as a whole as movement, namely as the people of God on the move (Lumen gentium 2, Conclusion, 8, 9, 48-51; UR, 2, Conclusion and passim). Or to formulate it another way: the Council ascribed new relevance to the eschatological dimension of the church and described the church not as a static but as a dynamic entity, as the people of God undertaking a pilgrimage between “already” and “not yet”. The Council integrated the ecumenical movement into this eschatological dynamic. Understood in this sense, ecumenism is the way of the church (UUS, 7). It is not an addendum or an appendix but forms an integral part of the very essence of the church and its pastoral activity (UUS, 20).

From this eschatological perspective, the ecumenical movement is intimately connected with the mission movement. Ecumenism and mission belong together like twins.[4]

Mission is an eschatological phenomenon in which the church takes up the cultural riches of the peoples, purifies and enriches them, and is thereby itself enriched and endowed with the full expression of its catholicity (Ad gentes 1 ff., 9 and passim). Similarly, in ecumenism the church enters into an exchange of gifts with the separated churches (UUS, 28, 57), enriches them, but also reciprocally makes their gifts its own, adds them to its catholic fullness and thus fully realises its own catholicity (UR, 4). Mission and ecumenism are the two forms of the eschatological pathway and the eschatological dynamic of the church.

The Council was not so naïve as to underestimate the danger inherent in this integration of the ecumenical movement into the eschatological dynamic of the church. The eschatological dynamic could – as so often in the history of the church – be misunderstood as a progressive movement in which the deposit of older traditions is felt to be outdated and is discarded in the name of a so-called progressive understanding of the faith. Where this occurs, there is a real danger of relativism and indifferentism, of a ‘cheap ecumenism’ which in the end makes itself redundant. In this way ecumenism has on occasion fallen prey to movements critical of the church and been instrumentalised against the church.

Any such softening of dogma fails to recognise the essence of the eschatological character of the church. The Eschaton does not refer to an historically unrealised future reality. With Jesus Christ and the outpouring of the Holy Spirit it has entered into history once and for all and is present in the church. The church itself is an eschatological phenomenon; unity as an essential characteristic of the church is not a future, or much less an eschatological goal; the church is already the “una sancta ecclesia” (UR, 4; UUS, 11-14). The ecumenical path is not a mystery tour. Through history the church becomes what it already is, what it always was and what it forever remains. It is on the way towards the concrete realisation of its essential nature within the reality of life in its fullness.

The Catholic principles of ecumenism, as formulated by the Council and later by Pope John Paul II, are therefore clear and unequivocal in their rejection of the irenicism and relativism which reduce everything to banality (UR, 5, 11, 24; UUS, 18, 36, 79). The ecumenical movement does not throw overboard anything which has been valued and cherished by the church in its previous history, it remains faithful to the truth that has been acknowledged in history and defined as such; nor does it add to it anything absolutely new. The ecumenical movement and its avowed goal, the unity of the disciples of Jesus Christ, remain inscribed within the furrow of tradition.

The tradition is however, in the sense of the two great precursors of the Council, J. A. Möhler and J. H. Newman, not a petrified entity; it is a living tradition. It is an event in the Holy Spirit, who according to the promise of the Lord guides the church into all truth (John 16:13), again and again elucidating the Gospel which has been handed down once and for all, and granting growth in understanding of the truth which has been revealed once and for all (Dei verbum [DV] 8; cf. DS 3020). According to the martyr bishop Irenaeus of Lyon it is the spirit of God who keeps the apostolic heritage, handed down once and for all, young and fresh. [5]

In this sense the ecumenical movement is a charismatic phenomenon and “an undertaking of the Holy Spirit”. The church has not only an institutional but also a charismatic side, as the Council demonstrated (LG, 4, 7, 12, 49; Apostolicam actuositatem 3; AG, 4, 29). So ecumenism is a new beginning, set in motion by the Holy Spirit and led by him (UR, 1, 4). The Holy Spirit, as it were the soul of the church (LG, 7), grants unity as well as the multiplicity of gifts and services (LG, 7; UR, 2). Thus the Council was able to say that spiritual ecumenism is the heart of ecumenism. Spiritual ecumenism means inner conversion, a change of heart, the sanctification of personal life, love, self-denial, humility, patience, but also renewal and reform of the church; and not least, prayer is the heart of the ecumenical movement (UR, 5-8; UUS, 15 ff., 21-27).

As a spiritual movement the ecumenical movement does not annul tradition, rather it grants a new and more profound insight into what has been handed down once and for all; it blazes the trail for the renewed Pentecost which Pope John XXIII predicted in his opening address to the Second Vatican Council; it paves the way for the new historical form of the church, not a new church but indeed a spiritually renewed and spiritually enriched church. Together with mission, ecumenism is the way of the church into the 21st century and into the third millennium.

III. “Subsistit in” – Expression of an Historically Concrete Ecclesiology

The eschatological and pneumatological dynamic demanded conceptual clarification. This was in fact achieved by the Council in the Constitution on the Church, with the much-debated formulation, the church of Jesus Christ “subsists” in the Catholic Church (LG, 8). The principal editor of the Church Constitution, G Philips, was farsighted enough to predict that a lot of ink would be spilt over the significance of this “subsistit in”.[6] Indeed, the flow of ink has not subsided to this day, and it is likely that much more printer’s ink will be needed to clarify the issues it raises.

In the course of the Council the “subsistit in” took the place of the previous “est”.[7] It contains in nuce the whole ecumenical problem.[8] The “est” claimed that the church of Christ Jesus “is” the Catholic Church. This strict identification of the church of Christ Jesus with the Catholic Church had been represented most recently in the encyclicals Mystici corporis (1943) and Humani generis (1950).[9] But even according to Mystici corporis there are people who, although they have not yet been baptised, are subsumed under the Catholic Church because that is their express desire (DS 3921). Therefore Pius XII had condemned an exclusive interpretation of the axiom “Extra ecclesiam nulla salus” already in 1949.[10]

The Council went a decisive step further with the aid of the “subsistit in”. It wished to do justice to the fact that there are found outside of the Catholic Church not only individual Christians but also “elements of the church”,[11] indeed churches and ecclesial communities which, although not in full communion, rightly belong to the one church and possess salvatory significance for their members (LG, 8, 15; UR, 3; UUS, 10-14). Thus the Council is aware that there are outside of the Catholic Church forms of sanctification which even extend as far as martyrdom (LG, 15; UR, 4; UUS, 12, 83). The question of the salvation of non-Catholics is now no longer answered personally as in Mystici corporis on the basis of the subjective desire of single individuals, but institutionally on the basis of objective ecclesiology.

The concept “subsistit in”, according to the intention of the Theological Commission of the Council, means: the church of Christ Jesus has its concrete location in the Catholic Church; it is there that it is found.[12] It is not a purely Platonic entity or a prospective future reality, it exists in a concrete historical form, it is located in the Catholic Church.

Understood in this sense “subsistit in” encompasses the essential thrust of the “est”. But it no longer formulates the self-concept [self-image] of the Catholic Church in “splendid isolation”, but also takes account of churches and ecclesial communities in which the one church of Jesus Christ is effectively present (UUS, 11), but which are not in full communion with it. In formulating its own identity, the Catholic Church at the same time establishes a relationship of dialogue with these churches and ecclesial communities.[13]

Accordingly it is a misunderstanding of “subsistit in” to make it the basis of an  ecclesiological pluralism or relativism which implies that the one church of Christ Jesus subsists in many churches, and thus the Catholic Church is merely one among many other churches. Such theories of ecclesiological pluralism contradict the self-concept which the Catholic Church – like the Orthodox Churches, incidentally – has always had of itself and which the Second Vatican Council also wished to maintain. The Catholic Church continues to claim, as it always has, to be the true church of Christ Jesus, in which the entire fullness of the means of salvation are present (UR, 3; UUS, 14), but it now sees itself in a context of dialogue with the other churches and ecclesial communities. It does not propound any new doctrine but establishes a new outlook, abandons triumphalism and formulates its traditional self-concept in a realistic, historically concrete – one could even say, humble – manner. The Council is aware that the church is on a journey through history towards a concrete historical realisation of what its most profound essence “is” (“est”).

This realistic and humble view is found above all in Lumen gentium 8, where the Council with the words “subsistit in” allows not only for elements of the church outside of its visible boundaries but also for sinful members and sinful structures within the church itself.[14] The people of God also incorporates sinners within its fold, with the result that the spiritual essence of the church does not rightly shed its light upon the separated brethren or the world. Thus the church bears some of the guilt for the divisions, and slows down the growth of the Kingdom of God (UR, 3 ff.). On the other hand, the separated communities have on occasion better developed individual aspects of the revealed truth, so that the Catholic Church, under the circumstances of division, is unable to fully accomplish its intrinsic catholicity (UR, 4; UUS, 14). Therefore the church is in need of purification and renewal, and must constantly walk the path of penance (LG, 8; UR, 3 ff., 6 ff.; UUS, 34 ff., 83 ff.).

This self-critical and penitent view forms the basis for the path of the ecumenical movement (UR, 5-12). That includes conversion and renewal, without which there can be no ecumenism, and dialogue, which is more than an exchange of ideas but rather an exchange of gifts.

From this eschatological and spiritual perspective the goal of ecumenism cannot be described simply as “the others’ returning to the fold of the Catholic Church. The goal of full unity can only be achieved through conversion, when all are impelled by the spirit of God to turn to the one head of the church, Christ Jesus.  To the degree that we are one with Christ we will all be one with one another and thus realise the intrinsic catholicity of the church in its concrete fullness. Theologically the Council defined this goal as communio unity.

IV. Ecumenism Under the Banner of Communio Ecclesiology

The fundamental idea of the Second Vatican Council and especially of the Decree on Ecumenism is: communio.[15] This is essential to the correct understanding of the talk of  “elemente ecclesiae”. This phrase gives a quantitative, almost materialistic impression, as though one could count these elements and check whether the number is complete. This “ecclesiology of elements” was criticised already during the Council and even more so after the Council.[16] But Unitatis redintegratio did not stop at this point; the Decree on Ecumenism does not view the separated churches and ecclesial communities simply as entities which have retained a limited stock of elements, different in each instance, but able to be quantitatively determined; rather, it sees each as an integral whole which gives expression to those elements within the totality of its ecclesiological understanding.

That occurs with the aid of the concept of “communio”. With this concept drawn from the Bible and the early church the Council circumscribes the most profound mystery of the church, which is formed as it were as an icon of the trinity in the image of the trinitarian communio (LG, 4; UR, 2). Communio and communio sanctorum originally meant not the communion of Christians with one another but sharing (participatio) in the goods of salvation, in the sancta or the sacramenta.

Fundamental to this is baptism. It is the sacrament of faith, whereby those who have been baptised belong to the one body of Christ which is the church. Non-Catholic Christians are therefore not outside of the one church, they already belong to it in a most fundamental way (LG, 11, 14; UR, 22). On the basis of the one common baptism ecumenism goes far beyond simple goodwill and friendliness, it is not a form of church diplomacy; it has an ontological foundation and an ontological depth, it is an event of the Spirit.

Baptism is of course only the point of departure and the foundation (UR, 22). Becoming a member of the church reaches its fulfilment in the eucharist; that is the source, centre and summit of Christian and ecclesial life (LG, 11, 26; Presbyterorum ordinis 5; AG, 39). Thus eucharistic ecclesiology forms the foundation of the Constitution on the Liturgy and the Constitution on the Church (Sacrosanctum concilium 47; LG, 3, 7, 11, 23, 26).

Unitatis redintegratio states that the eucharist both signifies and brings about the unity of the church (UR, 2). Later it says of the celebration of the eucharist by the Orthodox Churches: “Through the celebration of the eucharist of the Lord in each of these churches the church of God is built up and grows in stature, and through concelebration their communion with one another is made manifest” (UR, 15). Wherever the eucharist is celebrated is the church. This axiom has – as I will demonstrate shortly – fundamental significance for the understanding of the oriental churches and the distinction between them and the Protestant ecclesial communities.

This means: Every local church celebrating the eucharist is church in the full sense, but it is not the whole church (LG, 26, 28). Since there is only one Christ Jesus and only one eucharist, each church celebrating the eucharist necessarily stands in communion with all other churches. The one church exists in and of the local churches (LG, 23), and the local churches exist vice versa in and of the one church (Communiones notio, 9).[17]

If we transfer this concept of unity to the ecumenism problem, the ecumenical unity we strive for is more than a network of church denominations which mutually recognise one another by establishing altar and pulpit fellowship. The Catholic understanding of ecumenism takes as its starting point the already existing unity and the already existing partial communio with the other churches and ecclesial communities, in order to progress from this incomplete fellowship to full communion (UUS, 14) which includes unity in the faith, in the sacraments and in church ministry (LG, 14; UR, 2 ff.).

Unity in the sense of full communio does not mean uniformity but unity in diversity and diversity in unity. Within the one church there is a legitimate multiplicity of mentalities, customs, rites, canonical orders, theologies and spiritualities (LG, 13; UR, 4; 16 ff.). We can also say: the essence of unity understood as communio is catholicity, not in the denominational sense but in its original qualitative meaning; it means the realisation of all the gifts which the local and denominational churches can contribute.

The contribution which Unitatis redintegratio makes towards the solution of the ecumenical problem is accordingly not an “ecclesiology of elements” but the distinction between full and imperfect communion (UR, 3).[18] The consequence of this distinction is that the aim of ecumenism is not directed towards amalgamation but has as its goal a communio which does not mean either reciprocal absorption or fusion.[19] This formulation of the ecumenical problem is the most important theological contribution of the Council towards the question of ecumenism.


V. East and West – Two Forms of the One Ecumenical Movement

Integrating ecumenical theology into the communio ecclesiology permitted a distinction between two kinds of church division: the division between East and West and the divisions within the Western church since the 16th century. Between the two kinds there is not only a geographic and chronological distinction; the two divisions are different also in nature.  While in the case of the split with the Eastern church the fundamental ecclesial structure which had developed since the second century remained intact, in the case of the churches which emerged from the Reformation we are dealing with a different type of church.[20]

The Eastern schism encompasses both the ancient oriental churches which separated from the imperial church in the 4th and 5th centuries and the schism between Rome and the Eastern Patriarchates, frequently linked symbolically to the year 1054.

The Council is far removed from reducing the difference to cultural and political factors. From the start East and West received the one Gospel in different ways and developed different forms of liturgy, spirituality, theology and canonical law. But in the basic sacramental-eucharistic and episcopal structure, however, they are in agreement. The national and international dialogues initiated following the Council have confirmed this profound communion in the faith, in the sacraments and in the episcopal structure.

Therefore the Council speaks of relationships like those between local churches as sister churches (UR, 14). This formulation, which is left rather vague in the Decree on Ecumenism, was taken up and further developed by Pope Paul VI and the Ecumenical Patriarch Athenagoras in Tomos Agapis.[21]

Restoration of full communion presupposes careful consideration of the various factors involved in the division (UR, 14) and recognition of the legitimate differences (UR, 15-17). The Council determines that the differences are more often to be considered mutually complementary rather than in fact conflicting (UR, 17).[22] Therefore it declares that the “entire heritage of spirituality and liturgy, of discipline and theology, in the various traditions, belongs to the full apostolic and catholic character of the church” (UR, 17).[23] In order to restore unity one must therefore not impose any burdens beyond that which is strictly necessary (Acts 15:28; UR, 18).

The essential problem in the relationship between East and West is the Petrine office (UUS, 88). Pope John Paul II has issued an invitation to a fraternal dialogue on the future exercise of the Petrine office (UUS, 95). It is not possible in this context to enter into the complex historical questions raised here or the current possibilities for reinterpretation and re-reception of the dogmas of the First Vatican Council. It must suffice to mention that a symposium conducted by the Pontifical Council for Christian Unity in May 2003 with the Orthodox churches resulted in openings on both sides.[24] We hope that the international theological dialogue can soon be resumed and that it can give priority to addressing this question.

The Western schism which originated in the 16th century Reformation is of a different kind. As the Decree on Ecumenism clearly recognises, this constitutes a complex and subtly differentiated phenomenon in both the historical and the doctrinal sense. We are linked with the Reformation communities too by many important elements of the true church. These include in particular the proclamation of the Word of God, and baptism. In many post-Conciliar dialogue documents these commonalities have been extended and intensified.[25]

But there are also “very weighty differences” which are not only of a historical, sociological, psychological or cultural nature, but are in fact based primarily on differing interpretations of revealed truth (UR, 19). According to the Council these differences concern in part the doctrine of Jesus Christ and redemption, and in particular the Holy Scriptures in their relationship to the church and the authentic teaching office, the church and its orders, the role of Mary in the work of salvation (UR, 20f; UUS, 66), in part also moral questions (UR, 23). The latter have particularly in recent times come to the forefront and are creating problems both within the Reformation communities and in their relationships with the Catholic Church.

In contrast to the Eastern schism, the Reformation communities of course involve not only individual doctrinal differences but also a different fundamental structure and a different type of church. Regardless of the differences between the Reformers – often considerable – their understanding of the church is grounded not on the eucharist but primarily on the Word of God as creatura verbi.[26]

The distinction becomes more marked in the question of the eucharist. The ecclesial communities which emerged from the Reformation have – as the Council says – “not preserved the original and complete reality (substantia) of the mystery of the eucharist” (UR, 22) because of the absence of the sacrament of orders.

In the sense of eucharistic ecclesiology this lack of eucharistic substance results in the distinction between churches and ecclesial communities. The declaration Dominus Jesus (16) added conceptual sharpness to this distinction, and this has often been the subject of harsh criticism on the part of Protestant Christians. Doubtless the intended meaning could have been expressed in a more understandable way; but in regard to the facts of the matter it is impossible to overlook the real difference in the concept of the church. Protestant Christians do not wish to be a church in the same way as the Catholic church understands itself as a church; they represent a different type of church and for this reason  they are not a church in the Catholic meaning of the word.

Because of these differences the Council warns against frivolous and imprudent zeal. “Ecumenical activity cannot be other than fully and sincerely Catholic, that is, loyal to the truth we have received from the Apostles and the Fathers and in harmony with the faith which the Catholic Church has always professed” (UR, 24). The Council however also warns against polemics. It is significant that the word “dialogue” recurs repeatedly at the conclusion of the different paragraphs, almost as a refrain (UR, 19, 21, 22, 23). That expresses once more the new spirit in which the Council addresses the task of surmounting the differences.

VI. Quanta es nobis via?

The Decree was a beginning. Nevertheless it has exerted an enormous influence both within the Catholic Church and ecumenically, and has profoundly transformed the ecumenical situation in the course of the last forty years.[27]

Doubtless Unitatis redintegratio has also left some questions open, as well as encountering objections and undergoing further development. But we should not on account of these problems overlook the rich fruits which this Decree has borne. It has initiated an irrevocable and irreversible process to which there is no realistic alternative. The Decree on Ecumenism points us on the way forward into the 21st century. It is the command of the Lord to follow this path, with moderation, but also with courage, with patience and above all with unshakeable hope.

In the end ecumenism is an adventure of the Holy Spirit. Therefore I finish with the words which also conclude the Decree: “And hope does not disappoint, for God’s love has been poured forth in our hearts through the Holy Spirit, who has been given to us” (Rom 5:5) (UR, 24).



[1] Translated from the original German text.

[2] On the pre-history of the ecumenical movement in the Catholic Church: H. Petri, “Die römisch-katholische Kirche und die Ökumene” in: Handbuch der Ökumenik, Bd. 2, Paderborn 1986, 95-135.

[3] Cf. W. Becker, in: LThK Vat. II, Vol. 2 (1967), 11-39; L. Jaeger, Das Konzilsdekret über den Ökumenismus, Paderborn 1968, 15-78; Storia del Concilio Vaticano II, edited by G. Alberigo, Vol. 3, Bologna 1998, 277-365; Vol. 4, Bologna 1999, 436-446.

[4] J. Le Guillou, Mission et unité. Les exigences de la communion, Paris 1959; Y. Congar, Diversités et communion, Paris 1982, 239 ff. Pope John Paul II also stressed this connection in the Encyclical Redemptoris missio (1990) (Nos. 36 and 50).

[5] Ireneaus of Lyon, Adversus haereses III, 24, 1 (Sources chrétiennes n. 211, Paris 1974, 472).

[6] G. Philips, L’Église et son mystère aux deuxième Concile du Vatican, tome 1, Paris 1967, 119.

[7] Overview in Synopsis historica edited by G. Alberigo-F. Magistretti, Bologna 1975, 38; 439ff; 506 ff.

[8] G. Philips, op.cit.

[9] AAS 35 (1943) 199; 42 (1950) 571.

[10] Letter of the Holy See to the Archbishop of Boston (1949), in: DS 3866-73.

[11] This concept originates in the first instance with J. Calvin, but while it there refers to the miserable remnants of the true church, within ecumenical discussion it is understood as positive, dynamic and future-oriented. It was first brought into play in an extension of the anti-Donatist position of Augustine by Y. Congar (cf. A. Nichols, Yves Congar, London 1986, 101-106). In the Toronto Declaration (1950) it also entered into the usage of the World Council of Churches.

[12] Synopsis historica, op.cit. 439; G. Philips, op.cit. 119; A. Grillmeier, LThK, Vat. II, Vol.1, 1966, 175; L. Jaeger, op.cit. 214-217.

[13] Pope Paul VI demonstrated the principle of this dialogic nature of the church in his first Encyclical Ecclesiam suam (1964).

[14] On the concept of “structures of sin” cf. the  Apostolic Letter of  Pope John Paul II Reconciliatio et Paenitentia (1984) 16 and UUS, 34.

[15] See the Extraordinary Episcopal Synod of 1985 (II C 1). The Pontifical Council for Christian Unity dealt with this issue in detail at the 2001 Plenary. Cf. the introduction by W. Kasper, “Communio. The Guiding Concept of Catholic Ecumenical Theology. The Present and the Future Situation of the Ecumenical Movement” in Information Service N. 109, 2002/I-II, 11-20.

[16] Cf. above all H. Mühlen, Una mystica persona, München-Paderborn 1968, 496-502; 504-513.

[17] Congregation for the Doctrine of the Faith, Letter, 1992.

[18] In the Council documents themselves this distinction is not yet fully developed terminologically.  In UR 3 the terms “plena communio” and “quaedam communio, etsi non perfecta” are used.

[19] John Paul II, Encyclical Slavorum apostoli (1985) 27.

[20] J. Ratzinger, “Die ökumenische Situation – Orthodoxie, Katholizismus und Reformation” in Theologische Prinzipienlehre, München 1982, 203-208.

[21] Tomos Agapis, Vatican–Phanar (1958–1970), Rome–Istanbul, 1971, 386-392 (No. 176). In the joint declaration of Pope John Paul II and the Ecumenical Patriarch Bartholomew of 1995 the turn of phrase was taken up once more.

[22] The Catechism of the Catholic Church (No. 248) also numbers the question of the Filioque among the problems which signify a complementary rather than a contradictory difference.

[23] See also the Decree Orientalium ecclesiarum 1, and the Encyclical Orientale lumen (1995) 1.

[24] Cf. Il ministero Petrino. Cattolici e ortodossi in dialogo, edited by W. Kasper, Rome 2004.

[25] Particularly noteworthy are the Lima documents Baptism, Eucharist and Ministry (1982), the ARCIC Documents with the Anglican Communion, the Convergence Documents with the Lutherans (The Lord’s Supper; Spiritual Office in the Church, etc.) and especially the Joint Declaration on Justification (1999).

[26] M. Luther, De captivitate Babylonica ecclesiae praeludium (1520): WA 560 ff.

[27] Cf. Il Concilio Vaticano II. Recezione e attualità alla luce del Giubileo, edited by R. Fisichella, Rome 2000, 335-415, with papers by E. Fortino, J. Wicks, F. Ocáriz, Y. Spiteris, V. Pfnür.