Protestantism
On 31 October 1517, Martin Luther supposedly nailed his 95 theses against the selling of indulgences at the door of the All Saints', the Castle Church in Wittenberg. The theses debated and criticised the Church and the papacy, but concentrated upon the selling of indulgences and doctrinal policies about purgatory, particular judgment, and the authority of the pope. He would later write works on the Catholic devotion to Virgin Mary, the intercession of and devotion to the saints, the sacraments, mandatory clerical celibacy, monasticism, further on the authority of the pope, the ecclesiastical law, censure and excommunication, the role of secular rulers in religious matters, the relationship between Christianity and the law, good works, and the sacraments.

Q: What did the theses argue against selling?
indulgences