When his father died, Sigismund was granted permission by the Polish Diet to claim his inheritance as the rightful King of Sweden. The Swedes, who previously declared John III a Catholic conspirator and traitor, became lenient when the new monarch pledged to respect Lutheranism as the country's new state religion. Sigismund was crowned at Uppsala on 19 February 1594, but his promise to uphold the Protestant faith in Sweden was a deception, as demonstrated by the presence of a papal nuncio in the royal procession. He appointed his uncle, Duke Charles, to rule as regent on his behalf when he returned to Poland. Tensions grew promptly in Sweden as Sigismund remained a devout Roman Catholic and left the country abruptly, which made the Swedes suspicious. Sigismund had the ultimate intention of reinstating Catholicism by force if necessary. The Jesuits often acted as agents refuting Protestantism and regaining lost spiritual ground for Rome.