The researcher observes the first manifestations of opposition to Roman Church, especially in southern France. He studies the reasons for the emergence of opposition and shows the continuity in heresies, which manifested itself up to the fourteenth century. He investigates the historical significance of the Albigensians, including examining the influence of this religious movement on Slavic peoples.
By the early thirteenth century, there were more than forty different religious movements, which differed both in anti-dogmatic ideas and in scale. According to O., reconciliation between the Catholics and the Albigensians could not have been expected, since both sides were representatives of extremely opposite positions. He notes that the term ‘Albigensians’ meant anyone who disagreed with orthodoxy. O. identifies two branches of this religious movement: eastern and western ones. The first one was more under the influence of Gnosticism and other philosophical systems coming from the Asia Minor; those were the Albigensians, or the Cathars. The second branch was closer to a strict Christian protest, those were the Waldensians, whom O, calls the predecessors of Calvinism; at the same time, the author emphasizes that the Albigensians could not be considered reformers.
Believing that without understanding the position of the Papacy, it is difficult to create a complete picture of the religious movements of the era, in separate chapters the author shows the role of those religious institution in the social structure of Western Europe by the thirteenth century. Taking into account the role of the Inquisition, in the second volume he also turns to the history of this organization and its role in the Albigensian wars.