linguistic:paraphrasing
Protestant Reformation

The issue of the Reformation was first brought to the imperial attention under Charles V. As Holy Roman Emperor, Charles called Martin Luther to the Diet of Worms in 1521, promising him safe conduct if he would appear. After Luther defended the Ninety-five Theses and his writings, the Emperor commented: "that monk will never make me a heretic". Charles V relied on religious unity to govern his various realms, otherwise unified only in his person, and perceived Luther's teachings as a disruptive form of heresy. He outlawed Luther and issued the Edict of Worms, declaring:

You know that I am a descendant of the Most Christian Emperors of the great German people, of the Catholic Kings of Spain, of the Archdukes of Austria, and of the Dukes of Burgundy. All of these, their whole life long, were faithful sons of the Roman Church... After their deaths they left, by natural law and heritage, these holy catholic rites, for us to live and die by, following their example. And so until now I have lived as a true follower of these our ancestors. I am therefore resolved to maintain everything which these my forebears have established to the present.

Charles V, however, kept his word, and left Martin Luther free to leave the city. Frederick III, Elector of Saxony and protector of Luther, lamented the outcome of the Diet. On the road back from Worms, Luther was kidnapped by Frederick's men and hidden in a distant castle in Wartburg. There, he began to work on his German translation of the bible. The spread of Lutheranism led to two major revolts: that of the knights in 1522–1523 and that of the peasants led by Thomas Muntzer in 1524–1525. While the pro-Imperial Swabian League, in conjunction with Protestant princes afraid of social revolts, restored order, Charles V used the instrument of pardon to maintain peace.

Following this, Charles V took a tolerant approach and pursued a policy of reconciliation with the Lutherans. The 1530 Imperial Diet of Augsburg was requested by Emperor Charles V to decide on three issues: first, the defence of the Empire against the Ottoman threat; second, issues related to policy, currency and public well-being; and, third, disagreements about Christianity, in attempt to reach some compromise and a chance to deal with the German situation. The Diet was inaugurated by the emperor on 20 June. It produced numerous outcomes, most notably the 1530 declaration of the Lutheran estates known as the Augsburg Confession (Confessio Augustana), a central document of Lutheranism. Luther's assistant Philip Melanchthon went even further and presented it to Charles V. The Emperor strongly rejected it, and in 1531 the Schmalkaldic League was formed by Protestant princes. In 1532, Charles V recognized the League and effectively suspended the Edict of Worms with the standstill of Nuremberg. The standstill required the Protestants to continue to take part in the Imperial wars against the Turks and the French, and postponed religious affairs until an ecumenical council of the Catholic Church was called by the Pope to solve the issue.

Due to Papal delays in organizing a general council, Charles V decided to organize a German summit and presided over the Colloquy of Regensburg between Catholics and Lutherans in 1541, but no compromise was achieved. In 1545, the Council of Trent was finally opened and the Counter-Reformation began. The Catholic initiative was supported by a number of the princes of the Holy Roman Empire. However, the Schmalkaldic League refused to recognize the validity of the council and occupied territories of Catholic princes. Therefore, Charles V outlawed the Schmalkaldic League and opened hostilities against it in 1546. The next year his forces drove the League's troops out of southern Germany, and defeated John Frederick, Elector of Saxony, and Philip of Hesse at the Battle of Mühlberg, capturing both. At the Augsburg Interim in 1548, he created a solution giving certain allowances to Protestants until the Council of Trent would restore unity. However, members of both sides resented the Interim and some actively opposed it.

The council was re-opened in 1550 with the participation of Lutherans, and Charles V set up the Imperial court in Innsbruck, Austria, sufficiently close to Trent for him to follow the evolution of the debates. In 1552 Protestant princes, in alliance with Henry II of France, rebelled again and the Second Schmalkaldic War began. Maurice of Saxony, instrumental for the Imperial victory in the first conflict, switched side to the Protestant cause and bypassed the Imperial army by marching directly into Innsbruck with the goal of capturing the Emperor. Charles V was forced to flee the city during an attack of gout and barely made it alive to Villach in a state of semi-consciousness carried in a litter. After failing to recapture Metz from the French, Charles V returned to the Low Countries for the last years of his emperorship. In 1555, he instructed his brother Ferdinand to sign the Peace of Augsburg in his name. The agreements led to the religious division of Germany between Catholic and Protestant princedoms.