Russia's southwestern expansion, particularly its incorporation of eastern Ukraine, had unintended consequences. Most Ukrainians were Orthodox, but their close contact with the Roman Catholic Polish also brought them Western intellectual currents. Through the Ukrainian Academy in Kiev, Russia gained links to Polish and Central European influences and to the wider Orthodox world. Although the Ukrainian link induced creativity in many areas, it also weakened traditional Russian religious practices and culture. The Russian Orthodox Church discovered that its isolation from Constantinople had caused variations to appear between their liturgical books and practices.

The Russian Orthodox patriarch, Nikon, was determined to bring the Russian texts back into conformity with the Greek texts and practices of the time. But Nikon encountered opposition among the many Russians who viewed the corrections as improper foreign intrusions. When the Orthodox Church forced Nikon's reforms, a schism resulted in 1667. Those who did not accept the reforms came to be called the Old Believers; they were officially pronounced heretics and were persecuted by the church and the state. The chief opposition figure, the protopope Avvakum, was burned at the stake. The split afterwards became permanent, and many merchants and peasants joined the Old Believers.

The tsar's court also felt the impact of Ukraine and the West. Kiev was a major transmitter of new ideas and insight through the famed scholarly academy that Metropolitan Mohyla founded there in 1631. Other more direct channels to the West opened as international trade increased and more foreigners came to Russia. The Tsar's court was interested in the West's more advanced technology, particularly when military applications were involved. By the end of the 17th century, Ukrainian, Polish, and West European penetration had weakened the Russian cultural synthesis—at least among the elite—and had prepared the way for an even more radical transformation.