ENIn his widely read work Icon animorum (1614) the famous Scottish writer John Barclay wrote about Poles: They are wedded strangely to their own fancies; nor do they take to themselves a greater licentiousness in manners and uncivil conversation than in opinions of religion and heavenly matters, of which every man without any fear will both think and speak as himself listeth. [...] From hence it is that their minds at this day are divided into so many schisms and have among them all the heresies which polluted former times (Barclay: 2003, 187). This image of citizens of the Polish-Lithuanian Commonwealth, engrossed in numerous theological disputations and discussions, although somewhat exaggerated, was not unfounded. The coexistence of religions and denominations was characteristic of the pre-Reformation heritage of the Kingdom of Poland and the Grand Duchy of Lithuania. Both countries, united by a personal union at the end of the fourteenth century (which led to the full political union creating the Polish-Lithuanian Commonwealth in 1569), were inhabited by Roman Catholic and Orthodox Christians, Armenian Monophysites, Jews, Muslims and Karaites. From the beginning of the 1530s, Reformation ideas began to seep into Poland-Lithuania.The nobility mainly leaned towards Calvinism, from which the radical and dynamic Minor Reformed Church of Polish Brethren (the Arians, Antitrinitarians) emerged in the mid-1560s, whereas Lutheranism exerted the strongest impact on burghers in Royal Prussia and Greater Poland, where the Unity of Czech Brethren also appeared in 1548. In Ruthenia, both in the part belonging to the Crown and the other in the Grand Duchy of Lithuania, Orthodox Christianity traditionally held the dominant position, yet Calvinism also won significant support there in the second half of the sixteenth century. Tire Union of Brest (1596), by which some of the Ruthenian Orthodox bishops - while maintaining the Byzantine rite - recognized the authority of the Pope and Catholic dogmas, dramatically complicated the religious situation. [Extract, p. 9]