In 1519, Luther defended his beliefs against Johann Eck at the Leipzig Debate. He argued that even church councils were fallible and cast doubt upon the divine authority of the papacy, controversial statements that led his detractors to brand him a heretic.
On 15 June 1520, the Pope issued a bull threatening Martin Luther with excommunication. On 10 December of the same year, Luther set fire to this in front of one of the Wittenberg town gates to cheers from the watching crowd. At this point, Luther's writings were the most frequently printed works in the Holy Roman Empire.


