ratified the unification act on 4 July, and henceforth governed one of the largest and multicultural countries of 16th-century Europe. Religion In comparison to his staunchly Catholic father, Sigismund Augustus paid little attention to the matters of faith and religion. Having a large number of mistresses before, during and after being married, he was viewed by the clergy as an adulterer and libertine. Sigismund was also reasonably tolerant towards minorities and supported nobles of different faith and nationality to be part of the national assembly, the Sejm. He continued his father's policies, but was more accepting of the Protestant Reformation in Poland (only to the status of a minority religion). Several magnates converted to Calvinism or Lutheranism during the Reformation started by Martin Luther and John Calvin, most notably Stanisław Zamoyski, Jan Zamoyski, Mikołaj Rej, Andrzej Frycz Modrzewski, Johannes a Lasco (Jan Łaski) and Mikołaj "the Black" Radziwiłł. Throughout the 16th century, Frycz Modrzewski advocated for renouncing Rome's authority and establishing a separate and independent Polish Church. His initiative was chiefly inspired by the creation of the Anglican Church by Henry VIII in 1534. Sigismund Augustus was lenient towards the idea, particularly due to the sudden spread of Protestantism among courtiers, advisors, nobles and peasants. Calvinism became especially popular among the upper classes as it promoted democratic freedoms and called for rebellion against absolutism, which the privileged Polish nobility favoured. During the 1555 Sejm session in Piotrków, the nobles intensively discussed the rights of priests in the newly proposed Polish Church and demanded the abolition of celibacy. Some Catholic bishops were supportive of the concepts and acknowledged the need for uniting Poland, Lithuania, Prussia and their vassals under a common religion. Sigismund agreed to the postulates, however, under the condition that Pope Paul IV will be in favour. Instead, Paul IV was enraged that such a proposition emerged for him to accept; he declined and refused to grant consent. Facing potential excommunication, the assembly were forced to abandon their plans. Nevertheless, Protestantism continued to flourish and spread. In 1565, the Polish Brethren came into existence as a Nontrinitarian sect of Calvinism. One year after Sigismund's death the Warsaw Confederation was adopted as the first European act granting religious freedoms. Despite this, Protestantism in Poland ultimately declined during the fierce Counter-Reformation measures under the despotic and arch-Catholic Sigismund III Vasa, who ruled for nearly 45 years. For instance, the Polish Brethren