How did the Roman Inquisition try to stop the spread of Protestantism in Catholic territories?

The Roman Inquisition, established in 1542, was created primarily to combat Protestantism, which the Roman Catholic Church defined as heresy.1

To suppress the spread of Protestant ideas, the Inquisition employed several key strategies:

• Control of Doctrine and Practice: The agency focused on strictly regulating religious belief and practice within Catholic territories, proving highly effective in areas where the Church held significant influence.1
• Political Cooperation: The Inquisition leveraged political and military alliances to pressure secular leaders into withdrawing protection from Protestants. Princes and states often surrendered "distinguished offenders" to the Holy See to gain favor, as seen in the cases of Bartolomé de Carranza and Pietro Carnesecchi.1
• Censorship: In 1559, the Church established the Index Librorum Prohibitorum (Index of Forbidden Books) to restrict the circulation of Reformation-era writings. This included banning Bibles in vernacular languages, leading to the destruction of many texts and forcing numerous printers to flee to Germany or Switzerland.1

These efforts were part of a broader initiative to enforce the reforms mandated by the Council of Trent and maintain religious orthodoxy.1