Mary Tudor burned protestants because she was a devout Catholic and believed that Protestantism was a heresy. She saw it as her duty to defend the Catholic Church and its teachings, and she believed that burning Protestants was the best way to do this. She also saw Protestantism as a threat to her throne, as some Protestants believed that her right to rule was illegitimate. Mary's persecution of Protestants was both ruthless and effective, and it succeeded in driving Protestantism underground in England for many years. However, it also created a great deal of resentment and bitterness among English Protestants, and it ultimately contributed to the rise of a more radical and militant form of Protestantism in England.