State church of the Roman Empire
Nicene Christianity became the state church of the Roman Empire with the Edict of Thessalonica in 380 CE, when Emperor Theodosius I made it the Empire's sole authorized religion. The Eastern Orthodox Church, Oriental Orthodoxy, and the Catholic Church each claim to be the historical continuation of this church in its original form, but do not identify with it in the caesaropapist form that it took later. Unlike Constantine I, who with the Edict of Milan of 313 CE had established tolerance for Christianity without placing it above other religions and whose involvement in matters of the Christian faith extended to convoking councils of bishops who were to determine doctrine and to presiding at their meetings, but not to determining doctrine himself, Theodosius established a single Christian doctrine (specified as that professed by Pope Damasus I of Rome and Pope Peter II of Alexandria) as the Empire's official religion.
Earlier in the 4th century, following the Diocletianic Persecution of 303-313 and the Donatist controversy that arose in consequence, Constantine had convened councils of Christian bishops to define the orthodoxy, or "correct teaching", of the Christian faith, expanding on earlier Christian councils. A series of ecumenical councils met during the 4th and 5th centuries, but Christianity continued to suffer rifts and schisms surrounding the issues of Arianism, Nestorianism, and Miaphysitism. In the 5th century the Western Empire decayed as a polity: invaders sacked Rome in 410 and in 455, and Odoacer, an Arian barbarian warlord, forced Romulus Augustus, the last nominal Western Emperor, to abdicate in 476. However, apart from the aforementioned schisms, the church as an institution persisted in communion, if not without tension, between the east and west. In the 6th century the Byzantine armies of the Eastern Roman Emperor Justinian I recovered Italy and other sections of the western Mediterranean shore. The Eastern Roman Empire soon lost most of these gains, but it held Rome, as part of the Exarchate of Ravenna, until 751, a period known in church history as the Byzantine Papacy. The Muslim conquests of the 7th century would begin a process of converting most of the then-Christian world in West Asia and North Africa to Islam, severely restricting the reach both of the Byzantine Empire and of its church. Missionary activity directed from Constantinople, the Byzantine capital, did not lead to a lasting expansion of the formal power of the Empire's state church, since areas outside the empire's political and military control set up their own distinct state churches, as in the case of Bulgaria in 919.
Justinian I, who became emperor in Constantinople in 527, established the bishops of Rome, Constantinople, Alexandria, Antioch, and Jerusalem - referred to as the Pentarchy - as the leadership of the Imperial church and gave each bishop the title of "Patriarch". However, Justinian saw these bishops as under his tutelage: according to his arrangement, "the Emperor was the head of the Church in the sense that he had the right and duty of regulating by his laws the minutest details of worship and discipline, and also of dictating the theological opinions to be held in the Church". However, by Justinian's day, the churches that now form Oriental Orthodoxy had already seceded from the Imperial state church, while in the west Christianity was mostly subject to the laws and customs of nations that owed no allegiance to the Emperor in Constantinople. While eastern-born popes who were appointed or at least confirmed by the Eastern Emperor continued to be loyal to him as their political lord, they refused to accept his authority in religious matters, or the authority of such a council as the imperially convoked Council of Hieria of 754. Pope Gregory III (731-741) became the last Bishop of Rome to ask the Byzantine ruler to ratify his election. By then, the Roman Empire's state church as originally conceived had ceased to exist. In the East, only the largest fragment of the Christian church was under the Emperor's control, and with the crowning of Charlemagne on 25 December 800 AD as Imperator Romanorum by the latter's ally, Pope Leo III, the de facto political split between east and west became irrevocable. Spiritually, the Chalcedonian Church, as a communion broader than the imperial state church, continued to persist as a unified entity, at least in theory, until the Great Schism and its formal division with the mutual excommunication in 1054 of Rome and Constantinople. Where the Emperor's power remained, the state church developed in a caesaropapist form, although as the Byzantine Empire lost most of its territory to Islam, increasingly the members of the church lived outside the Byzantine state. The Eastern Roman Empire finally collapsed with the Fall of Constantinople to the Islamic Ottoman Turks in 1453.
Western missionary activities created a communion of churches that extended beyond the empire, the beginnings of which predated the establishment of the state church. The obliteration of the Empire's boundaries by Germanic peoples and an outburst of missionary activity among these peoples, who had no direct links with the Eastern Roman Empire, and among Pictic and Celtic peoples who had never been part of the Roman Empire, fostered the idea of a universal church free from association with a particular state. On the contrary, "in the East Roman or Byzantine view, when the Roman Empire became Christian, the perfect world order willed by God had been achieved: one universal empire was sovereign, and coterminous with it was the one universal church"; and the state church came, by the time of the demise of the Byzantine Empire in 1453, to merge psychologically with it to the extent that its bishops had difficulty in thinking of Christianity without an emperor.
Modern authors refer to this state church in a variety of ways: as the catholic church, the orthodox church, the imperial church, the imperial Roman church, or the Byzantine church, although some of these terms are also used for wider communions extending outside the Roman Empire. The legacy of the idea of a universal church polity carries on, directly or indirectly, in today's Catholic Church and Eastern Orthodox Church, as well as in others, such as the Anglican Communion.
Early Christianity in relation to the state
Before the end of the 1st century, the Roman authorities recognized Christianity as a separate religion from Judaism. The distinction, perhaps already made in practice at the time of the Great Fire of Rome in the year 64, was given official status by the emperor Nerva around the year 98 by granting Christians exemption from paying the Fiscus Iudaicus, the annual tax upon the Jews. Pliny the Younger, when propraetor in Bithynia in 103, assumes in his letters to Trajan that because Christians do not pay the tax, they are not Jews.
Since paying taxes had been one of the ways that Jews demonstrated their goodwill and loyalty toward the Empire, Christians had to negotiate their own alternatives to participating in the imperial cult. Their refusal to worship the Roman gods or to pay homage to the emperor as divine resulted at times in persecution and martyrdom. Church Father Tertullian, for instance, attempted to argue that Christianity was not inherently treasonous, and that Christians could offer their own form of prayer for the well-being of the emperor.
Christianity spread especially in the eastern parts of the Empire and beyond its border; in the west it was at first relatively limited, but significant Christian communities emerged in Rome, Carthage, and other urban centers, becoming by the end of the 3rd century, the dominant faith in some of them. Christians accounted for approximately 10% of the Roman population by 300, according to some estimates. According to Will Durant, the Christian Church prevailed over paganism because it offered a much more attractive doctrine and because the church leaders addressed human needs better than their rivals.
In 301, the Kingdom of Armenia, which Rome considered de jure a client kingdom though yielded de facto to the Parthians (its ruling dynasty was of Parthian extraction), became the first nation to adopt Christianity as its state church.
Establishment and early controversies
Major communions of the 4th, 5th, and 6th centuries Communion Major churches Primary centers Chalcedonian
Roman Imperial Church
Western non-imperial Churches
Rome, Alexandria, Antioch, Constantinople,
Georgian Kingdoms (Colchis and Iberia)
Persian church Syria,
Sassanid Empire (Persia)
Armenia, Syria, Egypt Donatism
(largely ended after 411)
North Africa Arianism much of Eastern Roman Empire until 380
In 311, the dying Emperor Galerius ended the Diocletianic Persecution that he is reputed to have instigated, and in 313, Emperor Constantine issued the Edict of Milan, granting to Christians and others "the right of open and free observance of their worship".
Constantine began to utilize Christian symbols such as the Chi-Rho early in his reign but still encouraged traditional Roman religious practices including sun worship. In 330, Constantine established the city of Constantinople as the new capital of the Roman Empire. The city would gradually come to be seen as the intellectual and cultural center of the Christian world.
Over the course of the 4th century the Christian body became consumed by debates surrounding orthodoxy, i.e. which religious doctrines are the correct ones. In the early 4th century, a group in North Africa, later called Donatists, who believed in a very rigid interpretation of Christianity that excluded many who had abandoned the faith during the Diocletianic persecution, created a crisis in the western Empire.
A church synod, or council, was held in Rome in 313, followed by another in Arles in 314, the latter presided over by Constantine while still a junior emperor (see Tetrarchy). These synods ruled that the Donatist faith was heresy and, when the Donatists refused to recant, Constantine launched the first campaign of persecution by Christians against Christians, and began imperial involvement in Christian theology. However, during the reign of Emperor Julian the Apostate, the Donatists, who formed the majority party in the Roman province of Africa for 30 years, were given official approval.
Debates within Christianity
Christian scholars and populace within the Empire were increasingly embroiled in debates regarding christology (i.e., regarding the nature of the Christ). Opinions ranged from belief that Jesus was entirely human to belief that he was entirely divine. The most persistent debate was that between the homoousian, or Athanasian, view (the Father and the Son are one and the same, eternal), which was adopted at the council meeting that Constantine called at Nicaea in 325, and the homoiousian, or Arian, view (the Father and the Son are similar, but the Father is greater than the Son). Emperors thereby became ever more involved with the increasingly divided Church.
Constantine was of divided opinions (even as to being Christian), but he largely backed the Athanasian side, though he was baptized on his deathbed by the Arian bishop Eusebius of Nicomedia. His successor Constantius II supported a Semi-Arian position. Emperor Julian returned to the traditional (pagan) Roman/Greek religion, quickly quashed by his successor Jovian, a supporter of the Athanasian side.
A Council of Rimini in 359 supported the Arian view. A Council of Constantinople in 360 supported a compromise (see Semi-Arianism). The Council of Constantinople in 381, called by Emperor Theodosius I reasserted the Nicene or Athanasian view and rejected the Arian view. This council further refined the definition of orthodoxy, issuing, according to tradition, the Niceno-Constantinopolitan Creed.
On 27 February of the previous year, Theodosius I established, with the Edict of Thessalonica, the Christianity of the First Council of Nicaea as the official state religion, reserving for its followers the title of Catholic Christians and declaring that those who did not follow the religion taught by Pope Damasus I of Rome and Pope Peter of Alexandria were to be called heretics:
It is our desire that all the various nations which are subject to our Clemency and Moderation, should continue to profess that religion which was delivered to the Romans by the divine Apostle Peter, as it has been preserved by faithful tradition, and which is now professed by the Pontiff Damasus and by Peter, Bishop of Alexandria, a man of apostolic holiness. According to the apostolic teaching and the doctrine of the Gospel, let us believe in the one deity of the Father, the Son and the Holy Spirit, in equal majesty and in a holy Trinity. We authorize the followers of this law to assume the title of Catholic Christians; but as for the others, since, in our judgment they are foolish madmen, we decree that they shall be branded with the ignominious name of heretics, and shall not presume to give to their conventicles the name of churches. They will suffer in the first place the chastisement of the divine condemnation and in the second the punishment of our authority which in accordance with the will of Heaven we shall decide to inflict.— Edict of Thessalonica
In 391, Theodosius closed all the "pagan" (non-Christian and non-Jewish) temples and formally forbade pagan worship.
At the end of the 4th century the Roman Empire had effectively split into two states although their economies (and the Church, which only then became a state church) were still strongly tied. The two halves of the Empire had always had cultural differences, exemplified in particular by the widespread use of the Greek language in the Eastern Empire and its more limited use in the West (Greek, as well as Latin, was used in the West, but Latin was the spoken vernacular).
By the time the state church of the Empire was established at the end of the 4th century, scholars in the West had largely abandoned Greek in favor of Latin. Even the Church in Rome, where Greek continued to be used in the liturgy longer than in the provinces, abandoned Greek. Jerome's Vulgate had begun to replace the older Latin translations of the Bible.
The 5th century would see further fracturing of the state church of the Roman Empire. Emperor Theodosius II called two synods in Ephesus, one in 431 and one in 449, the first of which condemned the teachings of Patriarch of Constantinople Nestorius, while the second supported the teachings of Eutyches against Archbishop Flavian of Constantinople.
Nestorius taught that Christ's divine and human nature were distinct persons, and hence Mary was the mother of Christ but not the mother of God. Eutyches taught on the contrary that there was in Christ only a single nature, different from that of human beings in general. The First Council of Ephesus rejected Nestorius' view, causing churches centered around the School of Edessa, a city at the edge of the empire, to break with the imperial church (see Nestorian schism).
Persecuted within the Roman Empire, many Nestorians fled to Persia and joined the Sassanid Church (the future Church of the East). The Second Council of Ephesus upheld the view of Eutyches, but was overturned two years later by the Council of Chalcedon, called by Emperor Marcian. Rejection of the Council of Chalcedon led to the exodus from the state church of the majority of Christians in Egypt and many in the Levant, who preferred miaphysite theology.
Thus, in addition to losing all the western empire, the state church suffered a significant diminishment even in the east within a century of its setting up. Those who upheld the Council of Chalcedon became known in Syriac as Melkites, the imperial church, followers of the emperor (in Syriac, malka). This schism resulted in an independent communion of churches, including the Egyptian, Syrian, Ethiopian and Armenian churches, that is today known as Oriental Orthodoxy. In spite of these schisms, however, the imperial church still represented the majority of Christians within the by now already diminished Roman Empire.
End of the Western Roman Empire
In the 5th century, the Western Empire rapidly decayed and by the end of the century was no more. Within a few decades, Germanic tribes, particularly the Goths and Vandals, conquered the western provinces. Rome was sacked in 410 and 455, and was to be sacked again in the following century in 546.
By 476 the Germanic chieftain Odoacer had conquered Italy and deposed the last western emperor, Romulus Augustus, though he nominally submitted to the authority of Constantinople. The Arian Germanic tribes established their own systems of churches and bishops in the western provinces but were generally tolerant of the population who chose to remain in communion with the imperial church.
In 533 Roman Emperor Justinian in Constantinople launched a military campaign to reclaim the western provinces from the Arian Germans, starting with North Africa and proceeding to Italy. His success in recapturing much of the western Mediterranean was temporary. The empire soon lost most of these gains, but held Rome, as part of the Exarchate of Ravenna, until 751.
Justinian definitively established Caesaropapism, believing "he had the right and duty of regulating by his laws the minutest details of worship and discipline, and also of dictating the theological opinions to be held in the Church". According to the entry in Liddell & Scott, the term orthodox first occurs in the Codex Justinianus: "We direct that all Catholic churches, throughout the entire world, shall be placed under the control of the orthodox bishops who have embraced the Nicene Creed."
By the end of the 6th century the Church within the Empire had become firmly tied with the imperial government, while in the west Christianity was mostly subject to the laws and customs of nations that owed no allegiance to the emperor.
Patriarchates in the Eastern Roman Empire
Emperor Justinian I assigned to five sees, those of Rome, Constantinople, Alexandria, Antioch and Jerusalem, a superior ecclesial authority that covered the whole of his empire. The First Council of Nicaea in 325 reaffirmed that the bishop of a provincial capital, the metropolitan bishop, had a certain authority over the bishops of the province. But it also recognized the existing supra-metropolitan authority of the sees of Rome, Alexandria and Antioch, and granted special recognition to Jerusalem.
Constantinople was added at the First Council of Constantinople (381) and given authority initially only over Thrace. By a canon of contested validity, the Council of Chalcedon (451) placed Asia and Pontus, which together made up Anatolia, under Constantinople, although their autonomy had been recognized at the council of 381.
Rome never recognized this pentarchy of five sees as constituting the leadership of the state church. It maintained that, in accordance with the First Council of Nicaea, only the three "Petrine" sees of Rome, Alexandria and Antioch had a real patriarchal function. The canons of the Quinisext Council of 692, which gave ecclesiastical sanction to Justinian's decree, were also never fully accepted by the Western Church.
Muslim conquests of the territories of the patriarchates of Alexandria, Antioch and Jerusalem, most of whose Christians were in any case lost to the imperial state church since the aftermath of the Council of Chalcedon, left in effect only two patriarchates, those of Rome and Constantinople. Then in 740, Emperor Leo the Isaurian reacted to papal resistance to his iconoclast policy by transferring from the jurisdiction of Rome to that of Constantinople all but a minute portion of the then existing empire.
The Patriarch of Constantinople had already adopted the title of "ecumenical patriarch", indicating what he saw as his position in the oikoumene, the Christian world ideally headed by the emperor and the patriarch of the emperor's capital. Also under the influence of the imperial model of governance of the state church, in which "the emperor becomes the actual executive organ of the universal Church", the pentarchy model of governance of the state church regressed to a monarchy of the Patriarch of Constantinople.
Rise of Islam
The Rashidun conquests began to expand the sway of Islam beyond Arabia in the 7th century, first clashing with the Roman Empire in 634. That empire and the Sassanid Persian Empire were at that time crippled by decades of war between them. By the late 8th century the Umayyad caliphate had conquered all of Persia and much of the Byzantine territory including Egypt, Palestine, and Syria.
Suddenly much of the Christian world was under Muslim rule. Over the coming centuries the successive Muslim states became some of the most powerful in the Mediterranean world.
Though the state church of the Roman Empire claimed religious authority over Christians in Egypt and the Levant, in reality the majority of Christians in these regions were by then miaphysites and members of other sects that had long been persecuted by Constantinople. The new Muslim rulers, in contrast, offered religious tolerance to Christians of all sects. Additionally subjects of the Muslim Empire could be accepted as Muslims simply by declaring a belief in a single deity and reverence for Muhammad (see shahada). As a result, the peoples of Egypt, Palestine and Syria largely accepted their new rulers and many declared themselves Muslims within a few generations. Muslim incursions later found success in parts of Europe, particularly Spain (see Al-Andalus).
Expansion of Christianity in Europe
During the 9th century, the Emperor in Constantinople encouraged missionary expeditions to nearby nations including the Muslim caliphate, and the Turkic Khazars. In 862 he sent Saints Cyril and Methodius to Slavic Great Moravia. By then most of the Slavic population of Bulgaria was Christian and Tsar Boris I himself was baptized in 864. Serbia was accounted Christian by about 870. In early 867 Patriarch Photios I of Constantinople wrote that Christianity was accepted by the Kievan Rus', which however was definitively Christianized only at the close of the following century.
Of these, the Church in Great Moravia chose immediately to link with Rome, not Constantinople: the missionaries sent there sided with the Pope during the Photian Schism (863–867). After decisive victories over the Byzantines at Acheloos and Katasyrtai, Bulgaria declared its Church autocephalous and elevated it to the rank of Patriarchate, an autonomy recognized in 927 by Constantinople, but abolished by Emperor Basil II Bulgaroktonos (the Bulgar-Slayer) after his 1018 conquest of Bulgaria.
In Serbia, which became an independent kingdom in the early 13th century, Stephen Uroš IV Dušan, after conquering a large part of Byzantine territory in Europe and assuming the title of Tsar, raised the Serbian archbishop to the rank of patriarch in 1346, a rank maintained until after the fall of the Byzantine Empire to the Turks. No Byzantine emperor ever ruled Russian Christianity.
Expansion of the Church in western and northern Europe began much earlier, with the conversion of the Irish in the 5th century, the Franks at the end of the same century, the Arian Visigoths in Spain soon afterwards, and the English at the end of the 6th century. By the time the Byzantine missions to central and eastern Europe began, Christian western Europe, in spite of losing most of Spain to Islam, encompassed Germany and part of Scandinavia, and, apart from the south of Italy, was independent of the Byzantine Empire and had been almost entirely so for centuries.
This situation fostered the idea of a universal church linked to no one particular state and of which the state church of the Roman Empire was only part. Long before the Byzantine Empire came to an end, Poland also, Hungary and other central European peoples were part of a Church that in no way saw itself as the empire's state church and that, with the East-West Schism, had even ceased to be in communion with it.
East–West Schism (1054)
With the defeat and death in 751 of the last Exarch of Ravenna and the end of the Exarchate, Rome ceased to be part of the Byzantine Empire. Forced to seek protection elsewhere, the Popes turned to the Franks and, with the coronation of Charlemagne by Pope Leo III on 25 December 800, transferred their political allegiance to a rival Roman Emperor. More clearly than before, the church in the west, while remaining in communion with the state church of the Byzantine Empire, was not part of it. Disputes between the see of Rome, which claimed authority over all other sees, and that of Constantinople, which was now without rival in the empire, culminated perhaps inevitably in mutual excommunications in 1054.
Communion with Constantinople was broken off by European Christians with the exception of those ruled by the empire (including the Bulgarians and Serbs) and of the fledgling Kievan or Russian Church, then a metropolitanate of the patriarchate of Constantinople. This church became independent only in 1448, just five years before the extinction of the empire, after which the Turkish authorities included all their Orthodox Christian subjects of whatever ethnicity in a single millet headed by the Patriarch of Constantinople.
The Westerners who set up Crusader states in Greece and the Middle East appointed Latin (Western) patriarchs and other hierarchs, thus giving concrete reality and permanence to the schism. Efforts were made in 1274 (Second Council of Lyon) and 1439 (Council of Florence) to restore communion between East and West, but the agreements reached by the participating eastern delegations and by the Emperor were rejected by the vast majority of Byzantine Christians.
In the East, the idea that the Byzantine emperor was the head of Christians everywhere persisted among churchmen as long as the empire existed, even when its actual territory was reduced to very little. In 1393, only 60 years before the fall of the capital, Patriarch Antony IV of Constantinople wrote to Basil I of Muscovy defending the liturgical commemoration in Russian churches of the Byzantine emperor on the grounds that he was "emperor (βασιλεύς) and autokrator of the Romans, that is of all Christians". According to Patriarch Antony, "it is not possible among Christians to have a Church and not to have an emperor. For the empire and the Church have great unity and commonality, and it is not possible to separate them", and "the holy emperor is not like the rulers and governors of other regions".
Following the schism between the Eastern and Western Churches, various emperors sought at times but without success to reunite the Church, invoking the notion of Christian unity between East and West in an attempt to obtain assistance from the Pope and Western Europe against the Muslims who were gradually conquering the empire's territory. But the period of the Western Crusades against the Muslims had passed before even the first of the two reunion councils was held.
Even when persecuted by the emperor, the Eastern Church, George Pachymeres said, "counted the days until they should be rid not of their emperor (for they could no more live without an emperor than a body without a heart), but of their current misfortunes". The state church had come to merge psychologically in the minds of the Eastern bishops with the empire to such an extent that they had difficulty in thinking of Christianity without an emperor.
In Western Europe, on the other hand, the idea of a universal church linked to the Emperor of Constantinople was replaced by that in which the Roman see was supreme. "Membership in a universal church replaced citizenship in a universal empire. Across Europe, from Italy to Ireland, a new society centered on Christianity was forming."
The Western Church came to emphasize the term Catholic in its identity, an assertion of universality, while the Eastern Church came to emphasize the term Orthodox in its identity, an assertion of holding to the true teachings of Jesus. Both churches claim to be the unique continuation of the previously united Chalcedonian Church, whose core doctrinal formulations have been retained also by many of the churches that emerged from the Protestant Reformation, including Lutheranism and Anglicanism.
- Arian controversy
- Chalcedonian Christianity
- Christianity in Iran
- Early Christianity
- Great Church
- History of late ancient Christianity
- History of the Catholic Church
- History of the Orthodox Church
- Forster (2008), p. 41.
- Tony Honoré (1998), p. 5.
- Vasiliev (1964), p. 66
- Bury (1923), p. 61
- Ayer (1913), p. 553
- Thomas Talbot, The Inescapable Love of God (Wipf and Stock 2014 ISBN 978-1-62564690-3), p. 18
- Ayer (1913), pp. 538-539
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- Schadé (2006), art. "Byzantine Church"
- In 1393, Patriarch Antony IV of Constantinople declared the Byzantine emperor to be "emperor (βασιλεύς) and autokrator of the Romans, that is of all Christians, and "it is not possible among Christians to have a Church and not to have an emperor. For the empire and the Church have great unity and commonality, and it is not possible to separate them" (Dimitri Obolensky, The Byzantine Inheritance of Eastern Europe (Variorum Reprints 1969 ISBN 978-0-86078102-8), p. 339).
- Meyendorff 1996, pp. 89.
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Schaff (1883), p. 179.
Irvin (2002), p. 160.
O'Hare (1997), p. 88.
- Wylen (1995). Pp 190-192.
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- Boatwright (2004). Pg 426.
- Tertullian, Apologeticus 30.1, as discussed by Cecilia Ames, "Roman Religion in the Vision of Tertullian," in A Companion to Roman Religion (Blackwell, 2007), pp. 467–468 et passim.
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Amory (), pp. 259–262.
- Lactantius, De Mortibus Persecutorum 45.1, 48.2, qtd. and tr. in Graeme Clarke, "Third-Century Christianity" in The Cambridge Ancient History, Volume XII: The Crisis of Empire, edited by Alan Bowman, Averil Cameron, and Peter Garnsey, 589–671. New York: Cambridge University Press, 2005. ISBN 0-521-30199-8, pp. 662–663
- Payton (2007), p. 29.
- Irvin (2002), p. 164, ch. 15.
- Encyclopaedia Britannica, Facts about Julian: Donatists
- George M. Ella, The Donatists and Their Relation to Church and State
- Irvin (2002), p. 164, ch. 16.
- Bettenson (1967), p. 22.
- "The first Christians in Rome were chiefly people who came from the East and spoke Greek. The founding of Constantinople naturally drew such people thither rather than to Rome, and then Christianity at Rome began to spread among the Roman population, so that at last the bulk of the Christian population in Rome spoke Latin. Hence the change in the language of the liturgy. ... The liturgy was said (in Latin) first in one church and then in more, until the Greek liturgy was driven out, and the clergy ceased to know Greek. About 415 or 420 we find a Pope saying that he is unable to answer a letter from some Eastern bishops, because he has no one who could write Greek" (Alfred Plummer, Conversations with Dr. Döllinger 1870-1890, ed. Robrecht Boudens (Leuven University Press, 1985), p. 13).
- Price (2005), p. 52
- Price (2005), p. 54
- Bussell (1910), p. 346.
- Latourette (1975), p. 183.
- Code of Justinian I.5.21
- Cairns (1996), p. 124. "By 590 the church had not only been freed from persecution by the Roman state but had become closely linked with that state."
- Canon 4
- Canon 6
- Canon 7
- Paul Valliere, Conciliarism (Cambridge University Press 2012 ISBN 978-1-10701574-6), pp. 91-92
- J.F. Puglisi (editor), How Can the Petrine Ministry Be a Service to the Unity of the Universal Church? (Eerdmans 2010 ISBN 978-0-80284862-8), p. 40
- Canon 3
- George C. Michalopulos, "Canon 28 and Eastern Papalism: Cause or Effect?"
- Canon 28
- Canon 2
- L'idea di pentarchia nella cristianità
- Wilhelm de Fries, The College of Patriarchs from the Point of View of Rome
- Encyclopaedia Britannica "Quinisext Council"
- Robert Browning, The Byzantine Empire (Revised Edition, CUA Press 1992 ISBN 978-0-81320754-4), p. 73
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- John Meyendorff, The Byzantine Legacy in the Orthodox Church (St Vladimir's Seminary Press 1982 ISBN 978-0-91383690-3), p. 20
- Jonathan Harris, Byzantium and the Crusades (Continuum International 2006 ISBN 978-1-85285501-7), p. 44
- Joseph Ratzinger, Church, Ecumenism and Politics, p. 95
- Milton V. Anastos, Constantinople and Rome
- Cardini (2001), p. 9.
- The entry of the Slavs into Christendom, p. 208
- Warren T. Treadgold, A History of the Byzantine State and Society (Stanford University Press 1997 ISBN 978-0-80472630-6), pp. 453, 558
- Kiminas, D. (2009). The Ecumenical Patriarchate. Wildside Press LLC. p. 15
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- Jeffrey Richards, The Popes and the Papacy in the Early Middle Ages (Routledge 1979 ISBN 978-0-71000098-9), p. 230
- Paul Johnson, History of Christianity (Simon & Schuster 2005 ISBN 978-0-74328203-1), p. 186
- E.E. Golubinskii, Istoriia russkoi tserkvi (Moscow: Universitetskaia tipografiia, 1900), vol. 2, pt. 1, p. 469
- Aidan Nichols, OP, Rome and the Eastern Churches (Ignatius Press 2010 ISBN 978-1-58617282-4), p. 281
- St Cletus Parish Adult Education, "Nails in the Coffin of Reunification"
- Eparchy of Newton, "The Melkites"
- Borys Andrij Gudziak, Crisis and Reform (Harvard University Press 1992), p. 17
- Michael Angold, Cambridge History of Christianity, Volume 5, Eastern Christianity (Cambridge University Press 2006 ISBN 978-0-52181113-2), p. 31
- Dimitri Obolensky, The Byzantine Inheritance of Eastern Europe (Variorum Reprints 1969 ISBN 978-0-86078102-8), p. 339
- J. Chrysostomides in Kathēgētria (Surrey 1988 ISBN 978-1-87132800-4), p. 516
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