<P> Much of the population of the Kingdom of Hungary adopted Protestantism during the 16th century . After the 1526 Battle of Mohács, the Hungarian people were disillusioned by the ability of the government to protect them and turned to the faith they felt would infuse them with the strength necessary to resist the invader . They found this in the teaching of the Protestant reformers such as Martin Luther . The spread of Protestantism in the country was aided by its large ethnic German minority, which could understand and translate the writings of Martin Luther . While Lutheranism gained a foothold among the German - and Slovak - speaking populations, Calvinism became widely accepted among ethnic Hungarians . </P> <P> In the more independent northwest the rulers and priests, protected now by the Habsburg Monarchy, which had taken the field to fight the Turks, defended the old Roman Catholic faith . They dragged the Protestants to prison and the stake wherever they could . Such strong measures only fanned the flames of protest, however . Leaders of the Protestants included Matthias Biro Devai, Michael Sztarai, and Stephen Kis Szegedi . </P> <P> Protestants likely formed a majority of Hungary's population at the close of the 16th century, but Counter-Reformation efforts in the 17th century reconverted a majority of the kingdom to Roman Catholicism . A significant Protestant minority remained, most of it adhering to the Calvinist faith . </P> <P> In 1558 the Transylvanian Diet of Turda declared free practice of both the Catholic and Lutheran religions, but prohibited Calvinism . Ten years later, in 1568, the Diet extended this freedom, declaring that "It is not allowed to anybody to intimidate anybody with captivity or expelling for his religion". Four religions (Unitarianism became official in 1583, following the faith of the only Unitarian King John II Sigismund Zápolya 1541--1571) were declared as accepted (recepta) religions, while Eastern Orthodox Christianity was "tolerated" (though the building of stone Orthodox churches was forbidden). During the Thirty Years' War, Royal (Habsburg) Hungary joined the Roman Catholic side, until Transylvania joined the Protestant side . </P>

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