The early 17th century in Ukraine and Belarus was dominated by the struggle over the Union. While most of the bishops adhered to the Union, the Orthodox were left without a hierarchy until 1620, when a new hierarchy was consecrated. The parallel Uniate and Orthodox hierarchies engaged in a competition over the possession of sees and church properties, as well as the loyalties of the populace.

This Church division was highlighted in the literary field. A rich and voluminous polemical literature (in Ruthenian and Polish, and sometimes Latin) grew up, often intemperate and even violent in tone, but marked by increasing erudition and a high literary style. Partisans on both sides turned to biblical exegesis, the early Church fathers, historical works, as well as apocrypha and legends. This polemical literature is represented most typically by Zakhariia Kopystensky (d. 1627), whose Palinodiia gave the fullest exposition of the Orthodox arguments; Metropolitan Ipatii Potii, the most able advocate of the Uniate position; and Archbishop Meletii SmotrytsÕkyi, who at various stages of his own confessional pilgrimage defended the Orthodox and then the Uniate position.

The confessional struggle at times turned to physical violence. In 1623, the Uniate archbishop of Polatsk, Josaphat Kuntsevych, was killed by enraged Orthodox partisans. He soon became an object of veneration by his followers, was beatified at Rome in 1642, and canonized in 1867. The Icones symbolicae vitae et mortis B. Iosaphat martyris is an example of his early hagiography among Uniates and Roman Catholics.

In the midst of confessional violence, two figures stand out for their pacific and conciliatory positions, as well as reforms and promotion of education--the Uniate metropolitan Yosyf Rutsky (d. 1637) and the Orthodox metropolitan Petro Mohyla (d. 1647). Mohyla, archimandrite of the Kyivan Caves Monastery since 1627, was elected metropolitan in 1633. He established the school that became the Kyiv Mohyla Academy, the largest center of education and scholarship among the East Slavs in its time. Mohyla was a prolific author of liturgical, homiletic, and polemical works. Most influential throughout the world of Orthodoxy was his profound elaboration of an Orthodox catechism, the Orthodoxa confessio...fidei.

Next to the Kyiv Mohyla Academy, the most significant cultural establishment was the printing press founded ca. 1615 at the Kyiv Monastery of the Caves; the largest press on Ukrainian territory through the middle of the 19th century, it survived until 1918, issuing several hundred titles on a wide variety of subjects. Liturgical texts were especially prominent, such as the Poluustav (1682) exhibited here.

Religious controversy also engulfed other ethnic Ukrainian regions, including Transcarpathia. This area was subject to the Hungarian crown since the early 11th century. Traditionally Orthodox, the Ukrainian population was also affected by the religious currents prevailing since the Reformation in Hungary. One result was the Union of Uzhorod in 1646 that brought a large portion (ultimately the majority) of the Orthodox under papal jurisdiction. The propagation of Catholic dogma resulted in the development of a religious literature, of which the first was the catechism, Katekhyzys dlia nauky uhro-rus'kym liudem (1698).