Being under strong pressure from Croatian Catholic clergy and state officials to recognize Papal jurisdiction, and to convert the population of his bishopric to Eastern Catholicism ("Uniate"), Simeon visited the Pope in 1611 and recognized his jurisdiction and maybe the Union of Florence as well. He confessed Catholicism in front of Robert Bellarmine. The strongest influence to his decision was Martin Dobrović who convinced him to recognize Papal jurisdiction and to accept Eastern Catholicism. In November 1611 the Pope appointed Simeon as bishop of Slavonia, Croatia and Hungary, while in reality his jurisdiction was limited to Orthodox population of Slavonia and Croatia. The Pope granted all former estates of the Catholic Monastery of All Saints to the Marča Monastery. On 21 November 1611 Marča was established as bishopric of the Eastern Catholic Church. It is estimated that in 1611 it had around 60,000 members. Simeon continued to use the Slavic language, Eastern Orthodox church rites, the Julian calendar, and did not severe ties with the Patriarchate of Peć, nor did he become a vicar of the Catholic bishop of Zagreb. Only part of the Marča brotherhood and local Orthodox Serbs followed him in the Uniatism. When the Serbian patriarch received news that Simeon had accepted union with the Catholic church he deposed Simeon from his position in 1628. Simeon died in 1630.