Why did Charles V summon Martin Luther to trial?
In 1521, the Holy Roman Emperor, Charles V, demanded that Luther appear before the diet of the Holy Roman Empire at Worms. There was no separation between church and state. Luther was asked to explain his views and Charles ordered him to recant. Luther refused and he was placed under an imperial ban as an outlaw. All of Europe was Catholic at the time; Luther's views, however, were not really new, but part of an outspoken trend that had been stirring within a lot of people for some time. These new view born out of the frustration of the masses with the Catholic Church excesses and corruption were to usher new religions changing the face of Christianity for ever.
Martin Luther, the chief catalyst of Protestantism, was a professor of biblical interpretation at the University of Wittenberg in Germany when he drew up his 95 theses condemning the Catholic Church for its corrupt practice of selling indulgences, or the forgiveness of sins. He followed up the revolutionary work with equally controversial and groundbreaking theological works, and his fiery words set off religious reformers all across Europe.
In January 1521, Pope Leo X excommunicated Luther. Three months later, Luther was called to defend his beliefs before Holy Roman Emperor Charles V at the Diet of Worms, where he was famously defiant. For his refusal to recant his writings, the emperor declared him an outlaw and a heretic. Luther was protected by powerful German princes, however, and by his death in 1546, the course of Western civilization had been significantly altered.