The Role of the Roman Inquisition in the Preparation of the Church Union of Brest (1595/1596)

In December 1595 in the Vatican, the joining of the Kiev Orthodox Metropolis with the Catholic Church was proclaimed, and thus the Uniate Church was born, which is still alive today. Historiography on the genesis of the so-called “Union of Brest” has not sufficiently studied the Vatican institutional and personal actors in this process, because the archives of the important Congregation of the Inquisition were only opened in 1998. There are still historic hypotheses that have not taken into account the Inquisition archives. The aim of our work is to study the role of the Congregation of the Inquisition in the preparation of the union of Brest. The source base consists of traditional sources related to the "unia", the Vatican organization and new inquisitorial sources. We analyze the main monographies on the Union of Brest of the last 50 years and the scholarly contemporary literature on the Roman curia. New institutional history and theory on modes of engagement and their conceptual constructions have been used to analyze sociological aspects of agent interaction. During this work, some hypotheses about the role of Vatican people and institutions in the preparation of the union were refuted, and the leading and almost exclusive role of the Congregation of the Inquisition, which left the imprint of its work and internal goals in the documents on the Union of Brest, was revealed and proved.