Editing House of Hohenzollern (section)

===Prussian Hohenzollern religion and religious policy===
The official religion of the state was "bi-confessional". John Sigismund's most significant action was his conversion from [[Lutheranism]] to [[Calvinism]], after he had earlier equalized the rights of Catholics and Protestants in the Duchy of Prussia under pressure from the King of Poland. He was probably won over to Calvinism during a visit to [[Heidelberg]] in 1606, but it was not until 25 December 1613 that he publicly took [[Eucharist|communion]] according to the Calvinist rite. The vast majority of his subjects in Brandenburg, including his wife [[Anna, Duchess of Prussia|Anna of Prussia]], remained deeply Lutheran, however. After the Elector and his Calvinist court officials drew up plans for mass conversion of the population to the new faith in February 1614, as provided for by the rule of ''[[Cuius regio, eius religio]]'' within the [[Holy Roman Empire]], there were serious protests, with his wife backing the Lutherans. This was doubly important as Anna brought with her the duchy of Prussia into the Brandenburg line of the house and the nascent Brandenburg-Prussian state. Resistance was so strong that in 1615, John Sigismund backed down and relinquished all attempts at forcible conversion. Instead, he allowed his subjects to be either Lutheran or Calvinist according to the dictates of their own consciences. Henceforward, Brandenburg-Prussia would be a bi-confessional state, with the ruling Hohenzollern house staying [[Calvinist]].<ref>Christopher Clark ''The Iron Kingdom: The Rise and Downfall of Prussia 1600-1947'' (Penguin, 2007) pp. 115–121</ref>

This situation persisted until Frederick William III of Prussia. Frederick William was determined to unify the Protestant churches to homogenize their liturgy, organization, and architecture. The long-term goal was to have fully centralized royal control of all the Protestant churches in the [[Prussian Union of churches]]. The merging of the Lutheran and Calvinist (Reformed) confessions to form the United Church of Prussia was highly controversial. Angry responses included a large and well-organized opposition. The crown's aggressive efforts to restructure religion were unprecedented in Prussian history. In a series of proclamations over several years, the ''Church of the Prussian Union'' was formed, bringing together the majority group of Lutherans and the minority group of Reformed Protestants. The main effect was that the government of Prussia had full control over church affairs, with the king himself recognized as the leading bishop.<ref>{{cite journal|author=Christopher Clark|title=Confessional policy and the limits of state action: Frederick William III and the Prussian Church Union 1817–40|journal=Historical Journal|volume= 39|issue=4 |year=1996|pages= 985–1004|jstor=2639865 |doi=10.1017/S0018246X00024730|s2cid=159976974 }}</ref>