Uniates History 1450-1789
Throughout the early modern period, the papacy received into communion with the Roman Catholic Church groups of Eastern Christians that retained their ecclesiastical structures and local practices. Unlike Protestants, whom the papacy viewed as break-away believers organized in sects devoid of sacraments and who should be reintegrated as individuals into the Latin Church, Orthodox and Oriental Orthodox Christians were considered bearers of the apostolic succession of bishops and valid sacraments; thus, these Christians could retain their traditions and ecclesiastical structures when reconciled with the Catholic Church. In contrast to the attempts for a universal union with the Orthodox Church attempted at the Second Council of Lyons (1274) and the Council of Florence (1439–1442), the unions of the early modern period were local unions of hierarchies, bishoprics, and even groups of believers. Post-Tridentine Catholicism viewed these groups not as local churches, but as Christians following specific rites that could be retained after proper submission.

The major stimuli for the unions were the policies of Catholic states that ruled over Orthodox and Oriental Christians, the desire of Eastern Christians to improve their situation under Catholic or even Islamic rulers by receiving the support of the papacy or Western Christian powers, and the attraction to the well-organized and dynamic Latin Christian world at a time of relative stagnation in Eastern Christendom. In most cases, programs for union initiated by either Rome or Eastern Christians were rejected by at least part of the clergy and laity, giving rise to competing ecclesial structures and fierce polemics. Orthodox responses to unionizing attempts often constituted a sharper definition of ecclesial traditions and dogmas, at times by adopting the tools and methods of their opponents.

The first and major union of the early modern period was that at Brest in the Polish-Lithuanian Commonwealth in 1596. Initiated by the metropolitan and bishops of the Kyiv metropolitanate, the Union of Brest held forth the promise of improving the situation of the Ruthenian (Ukrainian-Belarusian) Church in a Catholic-dominated state. Although supported by the monarch Sigismund III Vasa (ruled 1587–1632), the Uniates were unable to win over all the bishops to the union synod and were opposed by powerful nobles, the urban brotherhoods, numerous monasteries, and the Cossacks. They also suffered from the derisive attitude of many Latin clergy, who preferred outright conversion. Increasingly dependent on the civil authorities and Rome to combat the Orthodox opposition, the Uniates took on the spirit and institutions of the Latin Church, especially through the training of clergy in Roman and central-European seminaries. Led by dedicated hierarchs such as Metropolitans Ipatii Potii and Iosyf Rutsky and the Basilian Order, established in 1613 from the monastics who accepted the union, the Uniates survived the reestablishment of the Orthodox Metropolitanate in 1621 and the compromise of 1632, in which the state recognized the legality of the Orthodox and tried to divide the eparchies and churches between the two metropolitanates. The 1623 murder of Iosafat Kuntsevych, the archbishop of Polatsk, by the burghers of Vitsebsk who resisted his attempts to impose the union gave the Uniates a martyr and cult figure.

The Khmelnytsky Uprising, which began in 1648, put the very existence of the Uniate Church in question: in 1650, the king promised the rebels to return eparchies and churches to the Orthodox. Its situation worsened in 1654, when Muscovite and Ukrainian Cossack armies invaded the Grand Duchy of Lithuania and destroyed many Uniate centers on Belarusian territories. From 1655 to 1665 the Uniate Kyiv metropolitan see was left vacant; during the negotiations for the Union of Hadiach (1658) the Ukrainian side demanded the commonwealth abolish the union. Yet with the support of Rome and the restoration of Polish rule in the Belarus and right-bank Ukraine, the Uniates survived and increased in number in the late seventeenth century. By the turn of the century all the western Ukrainian eparchies accepted the union, and at the Synod of Zamość of 1720 the church's structure was strengthened, though Latinized at the same time. In the eighteenth century the Uniates comprised the overwhelming number of Eastern Christians in the commonwealth (approximately 4.6 million in the 1770s) and maintained a well-developed network of schools and printing presses. The partitions of the commonwealth in 1772, 1793, and 1795 radically worsened the Uniates' situation. Most came under Russian rule, and Catherine II (ruled 1762–1796) persecuted the church. Her successors in the nineteenth century abolished all the Uniate eparchies and converted all believers to Orthodoxy. In the western Ukrainian lands that went to the Habsburgs in 1772, the Uniates benefited from grants of equality with the Latin Church and were renamed the Greek Catholic Church and reorganized in the metropolitan province of Galicia in 1808. In the seventeenth century the Armenian archbishop of Lviv also entered into union with Rome.

The extension of Habsburg rule into central Europe and the Balkans created numerous Uniate communities. In 1610 a bishop was designated for Uniates in Croatia, and in 1646, at the Union of Uzhhorod, the Ukrainians of Hungary became Uniate. The most significant union was that of the Romanians of Transylvania at Alba Julia in 1700. Under the distinguished leadership of Bishop Ion Inochentie Micu-Klein (bishop 1729–1751), the church played a major role in defending Romanian cultural and political rights. Not all Transylvanians accepted the union, and Maria Theresa (ruled 1740–1780) was forced to permit them to have their own bishop in 1759.

In western Europe the major Uniate group was the Italo-Albanian, which was formed by the migration of Orthodox Albanians to southern Italy in the fifteenth century and later. In 1717 the Uniate Armenian Mechtarist fathers took up residence in Venice. Uniates also emerged in European colonies; one of the most important Uniate communities originated with the Christians of St. Thomas in the Malabar area of India, who were subordinated to the Latin Church by the Portuguese in the late sixteenth century. Missionary activities, some dating back to the Middle Ages and renewed in the early modern period, resulted in unions and the creation of ecclesiastical structures for Orthodox and Oriental Orthodox Christians, such as the union of parts of the Assyrian Church of the East in 1553, the election of a Catholic patriarch among the Syrian Orthodox 1662, the creation of an Armenian Patriarchate in Cilicia in 1742, and the creation of the Melkite Catholic Church in the early eighteenth century.

Current Catholic thinking has rejected the early modern form of conversion through union in deference to ecumenical contacts with the Orthdox. Nevertheless, Uniate groups have proved resilient in the Middle East and especially in eastern Europe, where they have reemerged after suppression by Communist governments. Most of these groups now view the term Uniate as derogatory.

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Blažejowski, Dmytro. Ukrainian and Armenian Pontifical Seminaries of Lviv (1665–1784). Rome, 1975.
Gudziak, Borys. Crisis and Reform: The Kyivan Metropolitanate, the Patriarchate of Constantinople, and the Genesis of the Union of Brest. Cambridge, Mass., 1998.
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Robertson, Ronald G. The Eastern Christian Churches: A Brief Survey. 5th ed. Rome, 1995.