Branch theory

Anglican

William Palmer (1803–1885), an Oxford theologian, was the principal originator of the Branch Theory. His two-volume Treatise on the Church of Christ (1838) formulated the notion. The theory was then popularized during the Oxford Movement, particularly through the work of the Tractarians. Although the Anglican Roman Catholic International Commission, an organization sponsored by the Anglican Consultative Council and the Pontifical Council for Promoting Christian Unity, seeks to make ecumenical progress between the Roman Catholic Church and the Anglican Communion, it has made no statement on the topic. The theory "has received mixed reception even within the Anglican Communion."

Roman Catholic

Soon after the formulation of the branch theory, the Catholic Church rejected the idea that "the three Christian communions, Roman Catholic, Greek schismatic, and Anglican, however separated and divided from one another, nevertheless with equal right claim for themselves the name Catholic" and "together now constitute the Catholic Church". The Catholic Church does not accept that those separated by schism or heresy are part of the one church, maintaining that "there exists a single Church of Christ, which subsists in the Catholic Church, governed by the Successor of Peter and by the Bishops in communion with him". It considers Anglican orders invalid in general and holds that, though individual Anglicans may have orthodox faith, the Anglican churches have not maintained the fulness of ancient Christian teachings, most notably on the sacraments. It insists that "the Church of Christ, despite the divisions which exist among Christians, continues to exist fully only in the Catholic Church".

It does not see acceptance of the branch theory or similar ideas as a requisite for ecumenical relations with other Christians, as witnessed in the wide-ranging activity of its Pontifical Council for Promoting Christian Unity.

Eastern Orthodox

Non-acceptance of the branch theory by the Eastern Orthodox Church, was in 1853 called unfortunate by the theory's founder, William Palmer, who wished the Eastern Church to claim to be no more than a part of the whole, not the whole of the true Church. Bishop Kallistos Ware says that "Orthodox writers sometimes speak as if they accepted the 'Branch Theory', once popular among High Church Anglicans", but explains that this opinion "cannot be reconciled with traditional Orthodox theology". Western Orthodox cleric Julian Joseph Overbeck writes:

But what do we see in the Anglican Church? Heresies are not only tolerated and publicly preached from the pulpits, and the schismatical and heretical Church of Rome is by a great many fondled and looked up to, but a theory has sprung up, the so called Branch-Church theory, maintaining that the Catholic Church consists of three branches: the Roman, Greek, and Anglican Churches. Only fancy! the Roman and Greek Churches contradicting and anathematising each other, and the Anglican Church (in its Articles) contradicting both, and besides full of heretical teaching-these are the component parts of the One Catholic Church, the abode of the Spirit of Truth!!! And on this theory rests the "Corporate Reunion of Christendom," which entirely ignores all Apostolic teaching concerning schism and heresy!

In its official declarations, the Eastern Orthodox Church states that the one true church founded by Jesus Christ is a real identifiable entity and that it is singularly the Eastern Orthodox Church. It has identified itself as the "one, holy, catholic, and apostolic church" in, for instance, synods held in 1836 and 1838 and in its correspondence with Pope Pius IX and Pope Leo XIII. Adrian Fortescue wrote of the Eastern Orthodox: "The idea of a church made up of mutually excommunicate bodies that teach different articles of faith and yet altogether form one Church is as inconceivable to them as it is to us (Catholics)". The Eastern Orthodox Church does regard Catholics or Protestants as branches of the "One True Church".

The Eastern Orthodox Church is a part of several ecumenical efforts on international, national, and regional levels, such as the World Council of Churches. With respect to branch theory, some conservative Eastern Orthodox, however, take a decidedly anti-ecumenical stand. For example, in 1983 the Holy Synod of Bishops of the Russian Orthodox Church Outside Russia stated:

Those who attack the Church of Christ by teaching that Christ's Church is divided into so-called "branches" which differ in doctrine and way of life, or that the Church does not exist visibly, but will be formed in the future when all "branches" or sects or denominations, and even religions will be united into one body; and who do not distinguish the priesthood and mysteries of the Church from those of the heretics, but say that the baptism and eucharist of heretics is effectual for salvation; therefore, to those who knowingly have communion with these aforementioned heretics or who advocate, disseminate, or defend their new heresy of Ecumenism under the pretext of brotherly love or the supposed unification of separated Christians, Anathema!

Oriental Orthodoxy

It is generally recognized that the Chalcedonian Schism resulted from a difference in semantics rather than actual doctrine, since both non-Chalcedonian and Chalcedonian Christianity share a similar Christology despite choosing to express it in different (Cyrillian vs. Chalcedonian) terms, and theological dialogue has resulted in formal statements of agreement on that issue, which have been officially accepted by churches on both sides. The Orthodoxy Cognate PAGE Society (Society for Orthodox Christian Unity and Faith), which is headquartered in India declares the Society's firm belief that, although "the two groups are not in communion with each other", "both the Byzantine (Eastern) Orthodox Churches and the Oriental Orthodox Churches are the true heirs to the One, Holy, Catholic and Apostolic Church of Christ, which was the Church of the apostles and the holy fathers. We also believe these Churches teach the true faith and morals of the Church established by Christ for which the ancient martyrs gave their lives."

Protestant

The Methodist Church holds to a variation of the branch theory ecclesiology, "advocating that Christianity is represented by three branches: Orthodox, Roman Catholic, and Protestant."

Other Protestant Christians generally reject the Anglican version of the branch theory as originally formulated and hold a theory in which the Christian Church "has no visible unity" but contains numerous denominations that are "invisibly connected." Fortescue states that "this theory is common among all Protestant bodies, although each one generally holds that it is the purest branch."

Protestantism as a branch

Some Protestant traditions, such as the Methodist Church, advocate a version of branch theory ecclesiology that holds that "Christianity is represented by three branches: Orthodox, Roman Catholic, and Protestant."

Sister churches theory

What has been called another version of the branch theory was propounded in the wake of the Second Vatican Council by some Roman Catholic theologians, such as Robert F. Taft Michael A. Fahey, and others. In this theory, the Eastern Orthodox Church and the Roman Catholic Church are two "sister churches". This theory was rejected outright by the Catholic Church, which applies the term "sister Churches" only to the relations between particular Churches, such as the sees of Constantinople and Rome. Eastern Orthodox also reject it.

A writer in the United States publication Orthodox Life says that ecumenism promotes the idea of a Church comprising all baptized Christians and within which the different confessions are "sister churches".

Two lungs theory

The metaphor of Christianity compared to one body breathing with two lungs was coined by the Russian poet and philosopher Vyacheslav Ivanov, inspired by the worldview of the 19th century Russian philosopher Vladimir Solovyov. Solovyov "felt that eastern Christians could learn from the Western church's relatively active presence in the world."

Ivanov accepted "the idea of 'Unia'", according to Robert Bird, the "combination of traditional rite and papal authority explains why Ivanov felt he was now breathing with both lungs." Pope John Paul II, according to Bird, "adopted Ivanov's imagery of the two 'lungs' of the universal Church" but John Paul II's "image of the full Church seems to presume their equal coexistence, supposedly without the submission of the East to papal authority."

John Paul II used the two lungs of a single body metaphor in the context of "the different forms of the Church's great tradition" in Redemptoris Mater (1987). John Paul II used the metaphor to "the Church", which for him was not some amalgam of the Catholic and Eastern Orthodox Church, but the Catholic Church itself, thus indicating that the Catholic Church must avail itself of the traditions of both Eastern Christianity and Western Christianity. The Catholic Church uses this metaphor to compare the Latin Church's tradition to the Eastern Orthodox Churches' traditions and also Eastern Catholic Churches' traditions, as emphasized in the Second Vatican Council's Orientalium ecclesiarum, the decree on Eastern Catholic Churches. John Paul II elaborated the metaphor, in Sacri Canones (1990), "the Church itself, gathered in the one Spirit, breathes as though with two lungs – of the East and of the West – and that it burns with the love of Christ in one heart having two ventricles."

An anonymous author wrote, in Orthodox Life magazine, that the metaphor comparing the Eastern Orthodox Church and the Roman Catholic Church to two lungs of one body was "shaped and influenced by" the branch theory and developed by "Orthodox ecumenists and Papists". Eastern Orthodox reject as incompatible with the Orthodox faith any such use of the "two lungs" expression to imply that the Eastern Orthodox and Roman Catholic churches are two parts of a single church and "that Orthodoxy is only for Easterners, and that Catholicism is only for Westerners", according to Archpriest Andrew Phillips. Patriarch Bartholomew I of Constantinople "rejects the opinion" that "there would be an 'incompatibility between Orthodox tradition and the European cultural way', which would be antinomic" and points out that idea "is against the principle of equality and respect of peoples and cultural traditions on our continent."

Ion Bria wrote in 1991 that the metaphor "may be attractive as an aid for understanding the formation of two distinctive traditions in Christianity after A.D. 1054." In 2005, Bishop Hilarion Alfeyev, chairman of the Representation of the Russian Orthodox Church to the European Institutions, told the 6th Gniezno Convention that the metaphor is "particularly relevant" when he "proposed to form a European Catholic-Orthodox Alliance" and said "nothing should prevent us from uniting our efforts in order to defend Christian tradition, without waiting for the restoration of full unity between the two lungs of European Christianity."