Worms, Diet of, 1521, most famous of the imperial diets held at Worms, Germany. It was opened in Jan., 1521, by Holy Roman Emperor Charles V. After disposing of other business, notably the question of the Reichsregiment, the diet took up the question of the recalcitrant behavior of Martin Luther. Charles was induced to summon Luther, who arrived at Worms under a safe-conduct on Apr. 16. At the diet Luther was asked if he would retract his teachings condemned by the pope. After a day's meditation he refused. For a week various theologians argued with him, but he would not retire from his ground. According to tradition Luther ended his defense on Apr. 18 with the words, "Here I stand. I cannot do otherwise. God help me. Amen." Finally, on Apr. 26, the emperor, seeing that the dispute was fruitless, ordered Luther to leave the city. He was formally declared an outlaw in the Edict of Worms (May 25); the lines of the Reformation were thereby hardened.