From The Writer's Almanac: Martin Luther, May 26
It was on this day in 1521 that Martin Luther was declared an outlaw by the Edict of Worms, (books by this author). The edict made Luther more of a hero than he already was, and it's a big reason that Protestantism caught on so quickly.
Luther decided to become a priest after getting caught out in a thunderstorm one night. He swore to God that if he survived he would enter the religious life. He did survive, and he went on to study theology, become ordained, and get a job as a professor in Wittenberg. As he became more and more involved in the Church he began to grow disgusted with some of its practices. He was especially angry about the Church's sales of indulgences, which were said to decrease the time a person had to spend in purgatory.
On the eve of All Saints' Day in 1517, Luther nailed to the door of his church ninety-five theses attacking the sale of indulgences and other excesses of the church. They were originally written in Latin, but they became so popular that people demanded they be translated into German, and so they were. Hundreds of copies were printed up on a printing press, which was still a fairly recent invention, and Luther's message spread throughout Germany and Europe.
Religious leaders and politicians began to realize how dangerous he was becoming to the traditional church, and in April of 1521, a group of Roman princes pressured Emperor Charles V into forming an assembly in the city of Worms to try to get Luther to reject his writings.
On his trip to Worms, Luther was celebrated as a hero at most of the towns he passed through. He refused to recant and went back to Wittenberg to start the reformation.