Vatslau Panutsevich, a Belarusian émigré researcher, focuses in his monograph on early 17th century history notable for a major religious shift in Rzeczpospolita. Jazafat Kuncewicz (Jozafat Kuntsevich) was a prominent figure at the time who advocated the idea of Church Unity in the Grand Duchy of Lithuania. For quite a long time Belarusian history researchers cast religious trends and Jazafat’s role in a negative light and attempts to explore the other side of the story met with opposition from the Orthodox clergy and “Great Russian” history school dominant in the Russian Empire and the Soviet Union. Vatslau Puntsevich’s monograph is not completely impartial despite the author’s effort, but it offers an opportunity to compare different views and work out a uniform approach to the controversial and tough issue of Church Unity.