Martin Luther, a professor of theology at the Univ. of Wittenberg, had been stirred to action by the campaign for dispensing indulgences being launched under Johann Tetzel in Germany. He protested. On Oct. 31, 1517, he posted on the door of the castle church at Wittenberg his 95 theses, inviting debate on matters of practice and doctrine. Luther's action was not as yet a revolt against the church but a movement for reform within. It was, however, much more than an objection to the money-grabbing and secular policies of the clergy. Luther had already become convinced that in certain matters of doctrine the purity of the ancient church had been perverted by self-seeking popes and clergy.
His disagreement with the church on matters of doctrine soon became apparent. In 1519 Luther in a dispute with Johann Eck openly espoused doctrines that were implicit in his theses, and he denied the authority of the church in religious matters. In 1520 the pope issued a bull of excommunication against Luther, and the Holy Roman emperor, Charles V, thundered against the rebel. Luther defied them, publicly burned the bull of excommunication, and issued vigorous pamphlets assailing the papacy and the doctrine of the sacraments. The breach was thus made in 1521, and the meeting of the Diet of Worms (see Worms, Diet of) not only failed to produce a compromise but forced many doubters into the camp of the rebels. Luther was declared an outlaw, but the threat was empty; under the protection of the powerful Frederick III, elector of Saxony, he was spirited off to the safety of the Wartburg.