The age of the Counter-Reformation was a time of bitter conflict in the eastern Orthodox churches in Ukraine and Russia. Rooted in societies with radically different political systems, cultural heritages and confessional traditions, Orthodox leaders and faithful in the two countries responded to the inspiration and pressure of reformed Roman Catholicism in apparently contradictory ways. At the same time, over the course of the seventeenth century, they discovered that their fates were inextricably linked for better or worse. Moreover, they constituted two points in a triangular relationship: in spite of its vulnerable position, the ecumenical patriarchate continued to enjoy much of its traditional prestige and considerable practical influence in both.

Both of the East Slavic Orthodox Churches reflected the political, social and spiritual issues of the society of which they were integral parts. In Russia the Orthodox Church was the only legal Christian confession. Following the Byzantine model, the hierarchy had close ties to the tsars’ government and the territorial jurisdictions of church and state were identical. The Muscovite church preserved the local variant of the Slavic Orthodox culture of earlier centuries and showed few signs of recent contact with other parts of Christian Europe.

In the Polish–Lithuanian Commonwealth, the eastern Orthodox Church faced radically different conditions. The kingdom was home to all of the major branches of Christendom – Roman Catholicism, eastern Orthodoxy, Protestantism and the Socinians – and a substantial Jewish population. This remarkable confessional diversity stemmed primarily from the power of the nobility and the concomitant weakness of the royal government.