The Holy See
back up






Your Eminence (Your Excellency):

In recent years, the attention of this Congregation has been directed to problems arising from the use of the phrase «sister Churches,» an expression which appears in important documents of the Magisterium, but which has also been employed in other writings, and in the discussions connected with the dialogue between the Catholic Church and the Orthodox Churches.  It is an expression that has become part of the common vocabulary to indicate the objective bond between the Church of Rome and Orthodox Churches.

Unfortunately, in certain publications and in the writings of some theologians involved in ecumenical dialogue, it has recently become common to use this expression to indicate the Catholic Church on the one hand and the Orthodox Church on the other, leading people to think that in fact the one Church of Christ does not exist, but may be re-established through the reconciliation of the two sister Churches.  In addition, the same expression has been applied improperly by some to the relationship between the Catholic Church on the one hand, and the Anglican Communion and non-catholic ecclesial communities on the other.  In this sense, a «theology of sister Churches» or an «ecclesiology of sister Churches» is spoken of, characterized by ambiguity and discontinuity with respect to the correct original meaning of the expression as found in the documents of the Magisterium.

In order to overcome these equivocations and ambiguities in the use and application of the expression «sister Churches,» the Congregation for the Doctrine of the Faith has judged it necessary to prepare the enclosed Note on the Expression «Sister Churches» which was approved by Pope John Paul II in the Audience of June 9, 2000.  The indications contained in this Note are, therefore, to be held as authoritative and binding, although the Note will not be published in official form in the Acta Apostolicae Sedis, given its limited purpose of specifying the correct theological terminology on this subject.

In providing you with a copy of this document, the Congregation asks you to kindly communicate the concerns and specific indications expressed therein to your Conference of Bishops and especially to the Commission or Office entrusted with ecumenical dialogue, so that the publications and other texts of the Episcopal Conference and its various offices will carefully abide by what is established in the Note.

With gratitude for your assistance and with prayerful best wishes, I remain

Sincerely yours in Christ,

+Joseph Card. Ratzinger




1. The expression sister Churches occurs often in ecumenical dialogue, above all, in the dialogue between Catholics and Orthodox, and is the object of continuing study by both parties. While there is certainly a legitimate use of this expression, an ambiguous use has become prevalent in contemporary writings on ecumenism. In conformity with the teaching of the Second Vatican Council and the post-conciliar Papal Magisterium, it is therefore appropriate to recall the correct and proper use of this expression. It is helpful to begin with a brief historical outline.

I. The origin and development of the expression 

2. The expression sister Churches does not appear as such in the New Testament; however, there are numerous indications of the sisterly relations which existed among the local Churches of Christian antiquity. The New Testament passage which most explicitly reflects this awareness is the final sentence of the Second Letter of John: «The sons of your elect sister send you their greetings» (2 Jn 13). These are greetings sent by one ecclesial community to another; the community which sends the greetings calls itself the sister of the other.

3. In Christian literature, the expression begins to be used in the East when, from the fifth century, the idea of the Pentarchy gained ground, according to which there are five Patriarchs at the head of the Church, with the Church of Rome having the first place among these patriarchal sister Churches. In this connection, however, it needs to be noted that no Roman Pontiff ever recognized this equalization of the sees or accepted that only a primacy of honour be accorded to the See of Rome. It should be noted too that this patriarchal structure typical of the East never developed in the West.

As is well known, the divergences between Rome and Constantinople led, in later centuries, to mutual excommunications with «consequences which, as far as we can judge, went beyond what was intended and foreseen by their authors, whose censures concerned the persons mentioned and not the Churches, and who did not intend to break the ecclesial communion between the sees of Rome and Constantinople.»[1]

4. The expression appears again in two letters of the Metropolitan Nicetas of Nicodemia (in the year 1136) and the Patriarch John X Camaterus (in office from 1198 to 1206), in which they protested that Rome, by presenting herself as mother and teacher, would annul their authority. In their view, Rome is only the first among sisters of equal dignity.

5. In recent times, the Orthodox Patriarch of Constantinople, Athenagoras I, was the first to once again use the expression sister Churches. In welcoming the fraternal gestures and the call to unity addressed to him by John XXIII, he often expressed in his letters the hope of seeing the unity between the sister Churches re-established in the near future.

6. The Second Vatican Council adopted the expression sister Churches to describe the relationship between particular Churches: «in the East there flourish many particular local Churches; among them the Patriarchal Churches hold first place, and of these, many glory in taking their origins from the apostles themselves. Therefore, there prevailed and still prevails among Eastern Christians an eager desire to perpetuate in a communion of faith and charity those family ties which ought to exist between local Churches, as between sisters.»[2]

7. The first papal document in which the term sisters is applied to the Churches is the Apostolic Brief Anno ineunte of Paul VI to the Patriarch Athenagoras I. After having indicated his willingness to do everything possible to «re-establish full communion between the Church of the West and that of the East,» the Pope asked: «Since this mystery of divine love is at work in every local Church, is not this the reason for the traditional expression “sister Churches,” which the Churches of various places used for one another? For centuries our Churches lived in this way like sisters, celebrating together the ecumenical councils which defended the deposit of faith against all corruption. Now, after a long period of division and mutual misunderstanding, the Lord, in spite of the obstacles which arose between us in the past, gives us the possibility of rediscovering ourselves as sister Churches.»[3]

8. The expression has been used often by John Paul II in numerous addresses and documents; the principal ones, in chronological order, are the following.

In the Encyclical Slavorum Apostoli: «For us they [Cyril and Methodius] are the champions and also the patrons of the ecumenical endeavour of the sister Churches of East and West, for the rediscovery through prayer and dialogue of visible unity in perfect and total communion.»[4]

In a Letter from 1991 to the Bishops of Europe: «Hence, with these Churches [the Orthodox Churches] relations are to be fostered as between sister Churches, to use the expression of Pope Paul VI in his Brief to the Patriarch of Constantinople, Athenagoras I.»[5]

In the Encyclical Ut unum sint, the theme is developed above all in number 56 which begins in this way: «Following the Second Vatican Council and in the light of earlier tradition, it has again become usual to refer to the particular or local Churches gathered around their Bishop as “sister Churches.” In addition, the lifting of the mutual excommunications, by eliminating a painful canonical and psychological obstacle, was a very significant step on the way toward full communion.» This section concludes by expressing the wish that the «traditional designation of “sister Churches” should ever accompany us along this path.» The topic is taken up again in number 60 of the Encyclical: «More recently, the joint international commission took a significant step forward with regard to the very sensitive question of the method to be followed in re-establishing full communion between the Catholic Church and the Orthodox Church, an issue which has frequently embittered relations between Catholics and Orthodox. The commission has laid the doctrinal foundations for a positive solution to this problem on the basis of the doctrine of sister Churches.»[6]

II. Directives on the use of the expression 

9. The historical references presented in the preceding paragraphs illustrate the significance which the expression sister Churches has assumed in the ecumenical dialogue. This makes the correct theological use of the term even more important.

10. In fact, in the proper sense, sister Churches are exclusively particular Churches (or groupings of particular Churches; for example, the Patriarchates or Metropolitan provinces) among themselves.[7] It must always be clear, when the expression sister Churches is used in this proper sense, that the one, holy, catholic and apostolic Universal Church is not sister but mother of all the particular Churches.[8]

11. One may also speak of sister Churches, in a proper sense, in reference to particular Catholic and non-catholic Churches; thus the particular Church of Rome can also be called the sister of all other particular Churches. However, as recalled above, one cannot properly say that the Catholic Church is the sister of a particular Church or group of Churches. This is not merely a question of terminology, but above all of respecting a basic truth of the Catholic faith: that of the unicity of the Church of Jesus Christ. In fact, there is but a single Church,[9] and therefore the plural term Churches can refer only to particular Churches.

Consequently, one should avoid, as a source of misunderstanding and theological confusion, the use of formulations such as «our two Churches,» which, if applied to the Catholic Church and the totality of Orthodox Churches (or a single Orthodox Church), imply a plurality not merely on the level of particular Churches, but also on the level of the one, holy, catholic and apostolic Church confessed in the Creed, whose real existence is thus obscured.

12. Finally, it must also be borne in mind that the expression sister Churches in the proper sense, as attested by the common Tradition of East and West, may only be used for those ecclesial communities that have preserved a valid Episcopate and Eucharist.

Rome, from the Offices of the Congregation for the Doctrine of the Faith, June 30, 2000, the Solemnity of the Sacred Heart of Jesus.


+ Joseph Card. Ratzinger

+ Tarcisio Bertone, S.D.B.
Archbishop Emeritus of Vercelli



[1] Paul VI and Athenagoras I, Joint Declaration Pénétrés de reconnaissance (7-12-65), 3: AAS 58 (1966), 20. The excommunications were mutually lifted in 1965: «Pope Paul VI and Patriarch Athenagoras I in his Synod...declare by mutual regret and to remove from memory and from the midst of the Church the sentences of excommunication» (ibid.,4); cf. also Paul VI, Apostolic Letter Ambulate in dilectione (7-12-65): AAS 58 (1966), 40-41; Athenagoras I, Patriarchal Τόμoς (7-12-65): ΤΟΜΟΣ ΑΓΑΠΗΣVatican-Phanar (1958-1970), 129 (Vatican Polyglot Press: Rome-Istanbul, 1971), 290-294.

[2] second Vatican Ecumenical Council, Decree Unitatis redintegratio, 14.

[3] paul VI, Apostolic Brief Anno ineunte (25-7-67): AAS 59 (1967), 852, 853.

[4] john Paul II, Encyclical Letter Slavorum Apostoli (2-6-85), 27: AAS 77 (1985), 807.

[5] john Paul II, Letter to the Bishops of Europe on Relations between Catholics and Orthodox in the New Situation in Central and Eastern Europe (31-5-91), 4: AAS 84 (1992), 167.

[6] john Paul II, Encyclical Letter Ut unum sint (25-5-95), 56 and 60: AAS 87 (1995), 954, 955, 957.

[7] Cf. the texts of the Decree Unitatis redintegratio, 14, and the Apostolic Brief of Paul VI to Athenagoras I Anno ineunte, cited above in footnotes 2 and 3.

[8] Cf. Congregation for the Doctrine of the Faith, Letter Communionis notio (28-5-1992), 9: AAS 85 (1993), 843-844.

[9] Cf. Second Vatican Ecumenical Council, Dogmatic Constitution Lumen gentium, 8; Congregation for the Doctrine of the Faith, Declaration Mysterium Ecclesiae (24-6-73), 1: AAS 65 (1973), 396-398.