“Cuius regio, eius religio” – “whose realm, his religion” – was the formula of the Peace of Augsburg in 1555, according to which it was left to the sovereign to establish the religion of his subjects. This was a victory for the Protestants and those Electors who were trying to maximize independence from the Emperor. But it also led to the persecution of heretics, who often had to flee to other places where they were also not welcome. Only after the Peace of Westphalia did the situation stabilize. The Protestant faith could now be carried out into the world. But it was still a long way to religious tolerance and ecumenism.