Catholic and Orthodox Christianity

For its first thousand years the Christian Church was, in principle, one. Yet the Latin-speaking West and the Greek-speaking East grew apart. After the Roman Empire split politically, the West fell under Germanic kingdoms while the East remained the Byzantine Empire with its capital at Constantinople. Fewer people could read the other’s language, theology developed in different directions, and customs diverged, from the bread used in the Eucharist to the rules on fasting and on married clergy.

Two questions proved hardest. The first was authority. Rome claimed that its bishop, as successor of the apostle Peter, held supreme authority over the whole Church. The Eastern churches honoured Rome as first among the great sees but held that the Church was governed by councils of bishops. The second was the filioque, the phrase “and the Son” added in the West to the Creed’s statement that the Holy Spirit proceeds from the Father. The addition appeared in Spain in the sixth century and was sung in Rome by the early eleventh century. Greek theologians objected both to its theology and to the changing of a creed agreed by an ecumenical council.

There had been earlier ruptures. In the 860s Pope Nicholas I and Patriarch Photius of Constantinople clashed over Photius’ appointment and over missions to the Bulgarians, and Photius denounced the filioque as an error. That quarrel was patched up, but it set out arguments that would return. Politics added strain: the crowning of Charlemagne as emperor by the pope in 800 offended Byzantium, and in the eleventh century Norman conquests in southern Italy brought Greek churches under Latin control and Latin customs into dispute.

Tensions came to a head in 1054. Pope Leo IX sent a delegation led by Cardinal Humbert to Constantinople, and talks with Patriarch Michael Cerularius broke down. On 16 July 1054 Humbert laid a bull excommunicating the patriarch on the altar of Hagia Sophia, and the patriarch’s synod excommunicated the legates in turn. At the time few saw this as final. The sack of Constantinople by Western crusaders in 1204 did far more damage, and later attempts at reunion, at Lyon in 1274 and Florence in 1439, failed to win acceptance in the East.

Catholics and Orthodox share most of their faith: the Trinity, the Incarnation, seven sacraments, bishops in apostolic succession, the veneration of Mary and the saints, and a rich monastic tradition. Their differences lie in how authority works and in doctrines defined after the break.

The Catholic Church teaches that the pope, as bishop of Rome, has full and universal authority, and the First Vatican Council in 1870 defined that he speaks infallibly when he solemnly defines a doctrine of faith or morals. The Orthodox Church is a communion of self-governing churches, such as those of Constantinople, Greece, Russia, Romania, Serbia and Antioch, united by faith and sacraments rather than by a single head. The ecumenical patriarch of Constantinople has a primacy of honour. Since the break, the Catholic Church has held further general councils, while the Orthodox recognise seven.

Some later Catholic teachings are not shared by the Orthodox, including purgatory as a defined doctrine and the Immaculate Conception of Mary, proclaimed in 1854. The Orthodox emphasise theosis, the transformation of the believer into the likeness of God, and a theology that often prefers mystery to definition. Worship also differs. Orthodox liturgy, usually the Divine Liturgy of St John Chrysostom, is sung throughout and takes place before an iconostasis, a screen of icons. Catholics of the Latin rite celebrate the Mass, since the 1960s mostly in local languages. Orthodox priests may marry before ordination, and Orthodox churches date Easter by the Julian calendar.

Discipline differs in other ways too. In the Orthodox churches infants receive communion straight after baptism and chrismation, while Latin Catholic children usually make their first communion around the age of seven. On marriage, the Catholic Church does not permit remarriage after divorce, though it may declare a marriage null, while the Orthodox churches, in an exercise of pastoral leniency they call oikonomia, may allow a second or third marriage with a more penitential service. Not all of these differences divide the churches along the line of rite: the Eastern Catholic churches, such as the Ukrainian Greek Catholic and Melkite churches, follow Byzantine worship and customs while recognising the pope.

The Catholic Church is the largest Christian body, with about 1.4 billion members according to Vatican figures, roughly half of all Christians. The Eastern Orthodox churches number somewhere around 200–230 million, depending on how members are counted, roughly a tenth of all Christians; the Pew Research Center’s often-quoted figure of about 12% also includes the Oriental Orthodox churches. Catholics live across the world, while Orthodox Christians are concentrated in Eastern Europe, Russia, Greece, the Balkans, the Caucasus and the Middle East, with growing diaspora communities.

Relations warmed in the twentieth century. In 1964 Pope Paul VI and Patriarch Athenagoras met in Jerusalem, and on 7 December 1965 they jointly lifted the excommunications of 1054. A joint international commission for theological dialogue began work in 1980 and has issued statements on the sacraments and on primacy. Popes and patriarchs now meet regularly, but full communion has not been restored, and the questions of papal authority and the filioque remain under discussion. Divisions within Orthodoxy, and the place of the Eastern Catholic churches, also complicate the dialogue.