In 1517, German theologian Martin Luther published his 95 Theses, attacking papal abuses and the sale of indulgences. With his charter, he initiated the Protestant Reformation. However, in 1521 Pope Leo X excommunicated Luther. He was then summoned to appear at the Diet of Worms, an assembly of the Holy Roman Empire, to recant his Theses. When he refused, Emperor Charles V declared him an outlaw and a heretic. But none of Luther’s adversaries could prevent his message spreading across the globe.