Martin Luther disagreed with abuses in the Catholic Church like selling indulgences and the Pope's lavish lifestyle. He wrote 95 Theses arguing indulgences had no biblical basis and salvation came through faith alone. When excommunicated, Luther said he would not recant without scriptural proof. His teachings formed Protestantism, rejecting priests' powers and the Pope as religious authority in favor of the Bible alone. John Calvin also taught predestination and salvation by faith alone, contributing to the Protestant Reformation.