 Calvinism gained many followers in the mid 16th century among both the "szlachta" and the magnates, especially in Lesser Poland and Lithuania.The Calvinists, who led by Jan Łaski were working on unification of the Protestant churches, proposed the establishment of a Polish national church, under which all Christian denominations, including Eastern Orthodox (very numerous in the Grand Duchy of Lithuania and Ukraine), would be united.After 1555 Sigismund II, who accepted their ideas, sent an envoy to the pope, but the papacy rejected the various Calvinist postulates.