Martin Luther persevered in his critique of the Catholic Church by remaining firm in his beliefs even against the threat of excommunication and imprisonment. When Luther posted his 95 Theses against the sale of indulgences on October 31, 1517, it was likely intended as a scholarly dispute--not an outright assault on Catholic doctrine. However, Luther's disagreements with the Church quickly spiraled into something much more serious. In 1521, he was excommunicated and later summoned to the Diet of Worms (a church council) and given the opportunity to recant his views. He likely experienced profound doubt as this event approached; if he refused to recant, he would remain excommunicated--disallowed from receiving the Eucharist (Lord's Supper)--or even imprisoned. Nevertheless, he persevered and refused to recant. Emperor Charles V declared him a heretic--someone who teaches doctrine contrary to official Church teachings--and outlawed him from the Holy Roman Empire. Luckily for Luther, some of the German princes protected him and hid him from the emperor. Were it not for Luther's perseverance, the Protestant Reformation may not have happened.