ABSTRACT
This chapter analyses the problems of conversion of Protestant and Orthodox candidates resonate over the whole period. The role of papal diplomacy for European politics in the sixteenth century, and in some aspects also in the seventeenth century, confirms Heinz Schilling’s statement on the ubiquity of the process of confessionalisation of the Old Continent, the post-medieval remnant of Res Publica Christiana. The intensification of papal diplomatic activity in Central and Eastern Europe that had taken place since the mid-sixteenth century was the response of the Holy See towards the progressive spread of the Reformation’s ideas in these territories. The sources exploited are primarily constituted by the correspondence of the diplomatic service of the Holy See and political diaries. In order to gain control over the dynamic progresses of the Reformation in such a strategic area as Poland–Lithuania, the pope decided to establish a permanent Apostolic Nunciature at the Jagiellonian court.
