The schism between the Ecumenical Patriarchate of Constantinople and the Russian Orthodox Church occurred between approximately 1467 and 1560. This schism de facto ended supposedly around 1560.
On 15 December 1448, Jonah became the metropolitan of Kiev and all Rus' within the Russian Orthodox Church without the agreement of the Ecumenical Patriarchate of Constantinople, which made the Russian Orthodox Church de facto independent. In response, in 1458, Gregory the Bulgarian was appointed and consecrated by the Pope of Rome as the Byzantine Catholic metropolitan of Kiev. Metropolitan Gregory was then recognised by Patriarch Dionysius I of Constantinople in 1466; since Constantinople maintained the Union with the Catholic Church until 1484, Kiev returned under Constantinople's jurisdiction. Dionysius therefore demanded in 1467 that all the hierarchs of the Muscovy submit to Gregory, but Moscow peremptorily refused. On the same year, Grand Prince Ivan III of Moscow declared a complete rupture of relations with the Patriarchate of Constantinople.
Relations were gradually restored and in 1560, the Patriarch of Constantinople considered the metropolitan of Moscow to be his exarch. From 1589 to 1591, the Russian Orthodox Church was recognized as autocephalous, and the patriarch of Moscow later became the eighth patriarch of the Eastern Orthodox Church.
Background
Metropolis of Kiev and all Rus'
The Metropolis of Kiev and all Rus' was a metropolis of the Eastern Orthodox Church that was erected on the territory of Kievan Rus'. It existed between 988 AD and 1596 AD. Canonically, it was under the jurisdiction of the Ecumenical Patriarchate of Constantinople. The episcopal seat (cathedra) was located in the city of Kiev.
Ecumenical council
An ecumenical council of the Catholic Church—the Council of Florence—took place from 1431 to 1449. Although he resisted at first, the Grand Prince of Moscow—Vasily II of Moscow—eventually permitted the Metropolitan of Kiev and all Rus'—Isidore of Kiev—to attend the council on condition that Isidore should return with "the rights of Divine law and the constitution of the holy Church" uninjured. The council healed the Great Schism by uniting the Roman Catholic and Eastern Orthodox churches. The union was proclaimed on 6 July 1439 in the document Laetentur Caeli which was composed by Pope Eugene IV and signed by the Holy Roman Emperor Sigismund and all but one of the bishops present. Some Greek bishops, perhaps feeling political pressure from the Byzantine Emperor, reluctantly accepted the decrees of the council. Other Eastern bishops, such as Isidore, did so with sincere conviction. Sylvester Syropoulos and other Greek writers charge Isidore with perjury because he accepted the union, despite his promise to Vasili II.
Following the signing of the bull, Isidore returned to the Grand Duchy of Moscow. In the Kremlin's Dormition Cathedral, Isidore read the decree of unification aloud. He also passed a message to Vasili II from the Holy See, containing a request to assist the metropolitan in spreading the Union in Rus'. Three days later, Isidore was arrested by the Grand Prince and imprisoned in the Chudov Monastery. He arranged for certain Rus' clergy to denounce the metropolitan for refusing to renounce the union with Rome. As a result, the Great Prince of Moscow voided the union in his lands and imprisoned Isidore for some time. Having adjudged Isidore to have apostatized to Catholicism, he was deposed by a local synod.
Premises of the schism
The Council of Bishops of Moscow condemned Isidor and imprisoned him. They later sent a letter to the Patriarch of Constantinople in which they listed Isidore's faults and requested that his case be considered. They also asked to be allowed to ordain a Metropolitan of Kiev and all Rus' by themselves; apparently, they had no doubt that Isidore would be deprived of his dignity. This letter has been interpreted in two ways. According to the historian Golubinsky, Moscow offered Constantinople a kind of compromise: Moscow gets the opportunity to ordain a Metropolitan and in return it does not raise the issue of the Union, while remaining in formal dependence on the uniate Patriarch of Constantinople. According to the historian Florya, the Eastern Orthodox of Moscow were sure of the imminent failure of the Union supporters, and were hoping for this failure.
However, the situation was different, and the new Patriarch of Constantinople was the uniate Metrophanes II, who continued to follow the decisions of the Council of Florence. The Eastern Orthodox of Moscow did not dare to judge Isidore themselves, so he was expelled from Moscow (it was officially announced that he had escaped); then, he was also expelled from Tver. He was also poorly met in Lithuanian Navahrudak, because Lithuanian Prince Casimir recognized the anti-pope Felix V who had been previously elected by the Council of Basel. In March 1443, Isidore had moved in Buda, possession of the new king of Poland and Hungary Vladislav III, and contributed to the publication of the privilege, which formally equated the rights of Catholic and Eastern Orthodox clergy in kings' lands. Then he went to Rome. It is known that at least one of the Eastern Orthodox bishops of the Grand Duchy of Lithuania accepted the ordination from Isidor, and repented of it, but other information on the situation in Lithuania is extremely rare.
Question of the subordination of the Metropolis of Kiev and all Rus' and the union
After the exile of Isidore from Moscow in 1441, the question of the subordination of the Metropolitan of Kiev and all Rus' to the Church of Constantinople remained unclear for a long time. In Constantinople itself, there was a fierce struggle between pro- and anti-unionists. In fact, the Union was supported by a narrow group of elite from the capital of the dying Empire. Russian Grand Prince Vasiliy II supported the anti-unionists (those information are preserved his correspondence with the monks of Mount Athos). After the death of the pro-unionist Metrophanes II in 1443, in Constantinople for a long time they did not manage to elect a new Patriarch. In 1444–1445 there were 15 public disputes between supporters and opponents of the Union.
Gradually, the ranks of the pro-unionists were reduced and ten years after the Council of Florence, only four of the members of the Greek delegation remained faithful to the Union. Despite this, the firm supporter of the Union Gregory Mammas became the new Patriarch (in 1444 or 1445). His position remained fragile and he fled Constantinople in 1451 after the death of Byzantine emperor John VIII Palaiologos (one of the initiators of the Union). Information about relations between Moscow and Constantinople during this period is extremely scarce and unreliable.
Election of Metropolitan Jonah of Kiev and all Rus'
After Vasily II regained his throne in 1447, Jonah was still officially only the bishop of Ryazan and his name was only in third place. It is only in 1448 that the Council of bishops of North-Eastern Rus' proclaimed Jonas Metropolitan of Kiev and All Rus'. This decision was not unanimous—the bishops of Tver and Novgorod (both cities were semi-independent from Moscow) did not sign the Charter of his election.
In support of Jonah's claims, Moscow claimed that the previous Metropolitan of Kiev and All Rus', Photios, had proclaimed Jonah as his successor, and that a Patriarch of Constantinople which they did not name had once promised Jonah that he would become Metropolitan of Kiev and All Rus' after Isidore. Some modern researchers doubt the validity of these claims.
The election of Jonah was not accompanied by a clear break with Constantinople. For example, Vasily II composed a letter to the new Emperor Constantine XI Palaiologos (whom he wrongly considered an opponent of the Union). Vasily justified the unauthorized election of Jonah by extreme circumstances and asked for communion and blessings, but only if there would be an Eastern Orthodox Patriarch in Constantinople:
We have done this from necessity, not from pride or insolence. Till the end of time we shall abide in the Orthodoxy that was given to us; our Church will always seek the blessing of the Church of Tsarigrad and will be obedient in all things to the ancient piety.
However Constantine XI, in a desperate search for allies against the Turks, agreed to the Union. Soon, in 1453, Constantinople fell and the question of recognizing Jonah remained uncertain until his death.
The Ecumenical Patriarchate wrote in an official letter in 2018: "the Holy Metropolitanate of Kiev has always belonged to the jurisdiction of the Mother Church of Constantinople, founded by it as a separate Metropolitanate, occupying the 60th position in the list of the eparchies of the Ecumenical Throne. Later on, the local Synod in the state of Great Russia—upon an unfounded pretext—unilaterally cut itself off from its canonical authority, i.e. the Holy Great Church of Christ (1448), but in the city of Kiev other Metropolitans, authentic and canonical, were continually and unceasingly ordained by the Ecumenical Patriarchate, since the Kievan clergy and laity did not accept their subjection to the center of Moscovy."
Schism
Gregory the Bulgarian, division of the Metropolis of Kiev, and beginning of the schism
After his election, Metropolitan Jonah tried to assert his jurisdiction over the Eastern Orthodox of Lithuania. He succeeded because the Grand Duke of Lithuania Casimir, who was recently (in 1447) elected king of Poland, and Vasily II (his brother-in-law) were able to agree on this. In 1451, Casimir IV sent a charter to the Eastern Orthodox of Lithuania in which he called them to obey Jonah as Metropolitan.
In 1454, after they conquered Constantinople, the Ottomans removed Ecumenical Patriarch Athanasius II and imposed a new Ecumenical Patriarch, Gennadios, "who promptly renounced the Filioque."
However, in 1458 the Patriarch-Uniate Gregory Mammas, who had fled from Constantinople to Rome, ordained Gregory the Bulgarian as new Metropolitan of Kiev and All Rus'. Previously, also in 1458, Pope Calixtus III had divided the Metropolis of Kiev into two parts: "Superior Russia" centered about Moscow and "Inner Russia" centered about Kiev.
Casimir IV was forced to cede to the demands of Pope Calixtus III and to recognize Gregory as Metropolitan, restoring the Union in Lithuania. Jonah resisted this decision, and in 1459 he assembled the Council and demanded that its members swear allegiance to him or to his successor, as well as to sever relations with the Uniate Metropolitan Gregory. In case of any persecution by the authorities, Jonah promised the bishops refuge in the Moscow Principality, but only one Bishop, Evfimy of Bryansk and Chernigov, took advantage of this offer (he became Bishop of Suzdal). In 1461, Jonah died. Despite the victory of Gregory the Bulgarian over the Eastern Orthodox bishops, he faced resistance to the Union at the grassroots level (at this time the first Orthodox "brotherhoods" were formed).
At the same time, in Constantinople, which was ruled by the Turks, the Union was finally rejected. As a result, Gregory decided to leave the Catholic Church, and returned to the jurisdiction of Patriarch Dionysius I of Constantinople. In February 1467 Dionysius sent a letter to Moscow, in which he called all the Russian lands, and especially Great Novgorod, to accept Gregory as the only legitimate Metropolitan recognized by Constantinople. In addition, in the same letter Dionysius claimed that his Holy Catholic Church "did not accept, does not hold, and does not name as metropolitans" Jonah and other metropolitans, ordained in Moscow after him. At this time, Philip I was the metropolitan in Moscow, since 1464; he replaced Theodosius, whom Jonah had appointed as his successor.
Complete rupture with the Ecumenical Patriarch by Ivan III
Grand Prince Ivan III of Russia refused to recognize Gregory the Bulgarian, which led to a rupture of relations between Moscow and Constantinople. In 1470, Ivan III wrote to the Archbishop of Novgorod that he did not recognize Gregory as a Metropolitan; Ivan added concerning the Patriarch of Constantinople: "we do not demand him, nor his blessing, nor his disregard, we consider him, the very patriarch, alien and renounced". These words were a clear confirmation of the formal break with Constantinople, which arose because of the autocephaly of the church of Moscow. Soon the Novgorod Republic tried to get out from the influence of Moscow, recognizing Casimir of Poland and Lithuania as their liege, and Gregory as their Metropolitan. But Ivan III suppressed this attempt by military force, executing leaders of the opposition (1471).