Duchy of Legnica
In 1613 John Christian, then a Lutheran, began to profess openly the Calvinism. With him, his younger brother George Rudolf also changed his religion. The brothers followed the example their second-cousin, John Sigismund, Elector of Brandenburg, who shortly before publicly took communion according to the Calvinist rite, after almost two years of professed in secret. Thanks to this, they could renewed the alliance of the Duchy of Legnica-Brzeg with the House of Hohenzollern.