In the last issue of this article, we had already reached the point in history of the Reformation in the West, Martin Luther’s break with the Roman Church. At first the clergy of Rus were loyal to Orthodoxy, that is to Constantinople, rather than to the Polish Catholic monarch. Persecution of the Orthodox population, however, grew and, under pressure of the Polish authorities, the clergy of the Ruthenian Church (Rus) agreed in 1595 to the Union of Brest. By this agreement, the Ruthenian Church broke from union with the Patriarchate of Constantinople and united with the Catholic Church under the authority of the ruler Sigismund III Vasa, in exchange for ending the persecution. The union was not accepted by all the members of the Greek Church in these lands, and marked the creation of two separate Churches, the Ukrainian Greek Catholic Church and the Ukrainian Orthodox Church in both Ukraine and Belarus. Due to the resulting violence, the Metropolitan of the Kievan Greek-Catholic Church left Kiev early in the 17th century and settled in Navahrudak (i.e., present-day Belarus and Vilnius in Lithuania).

The final step in the full development of a particular Ukrainian Greek-Catholic Church was effected by the development of the Ruthenian language (i.e., that created by Cyril and Methodius), into separate Rusyn, Ukrainian and Belarusian languages around 1600 to 1800. With the Orthodox Church being largely suppressed during the two centuries of Polish rule, the Greek-Catholic influence on the Ukrainian population was so great that in several oblasts hardly anyone remained Orthodox.

After the partition of Poland, the formerly Greek-Catholic territory was divided between Russia and Austria. The portion which came under Russian rule included Volhynia and Podolia. In the easternmost areas of Podolia the population quickly returned to Orthodoxy. Initially, Russian authorities were tolerant of the Greek-Catholic Church, allowing it to function without restraint. This situation changed abruptly following Russia’s successful suppression of the 1831 Polish uprising, aimed at overthrowing Russian control of the Polish territories. As the uprising was supported by the Greek-Catholic Church, a crackdown on the Church occurred immediately and the Church was driven into the underground. The parishes in Volhynia were forced to revert to  Orthodoxy, including the 1833 transfer of the famous Pochaiv Lavra. In 1839 the Synod of Polotsk, under the leadership of Bishop Semashko, the Greek-Catholic Church was dissolved in the Russian Empire and its properties were transferred to the Orthodox, state church.