Encouraged by Protestant supporters, including several in the Cathedral chapter, he declared he would retain the electorate, and in December 1582, he formally announced his conversion to the reformed faith and the parity of Calvinism with Catholicism in the Electorate and archdiocese of Cologne.
The clause concerning ecclesiastical reservation in the religious Peace of Augsburg was interpreted in one way by his friends, and in another way by his foes; the former held that he could retain his office, the latter insisted that he resign.