On October 31st, 1517, Luther dispatched his Disputationes Pro Declaratione Virtutis Indulgentiarum, better known as the “Ninety-Five Theses,” challenging the practice of selling indulgences. Luther called for debate, since the Catholic Church had not yet promulgated a doctrine on this subject. This would eventually shake the Catholic Church to its core.

The imagery of Luther defiantly nailing his Theses to the church door at Wittenberg comes from an account by Philipp Melanchthon, written after Luther’s death.

Luther wrote to Albrecht, the Archbishop of Mainz, to alert him of the practice of selling indulgences, but Albrecht had a vested interest in silencing anyone who might hinder his flow of revenue from the sales. He needed this money to pay back the huge debt he had incurred by securing his secular and religious power. He had made an agreement with Pope Leo X to split the profits from the sales, dividing the spoils of the credulous souls of Germany.