Pope Leo X. excommunicated Luther in January 1521. Normally this would have been followed by the Imperial ban. But the imperial potentates and the noble classes convinced King Charles V to interrogate Luther at the Imperial Diet. Charles guaranteed Luther's safe passage.
The hearing took place in the Bishop's palace on 17 and 18 April 1521. Luther refused to recant. The King proclaimed his Imperial ban the next day, and it was issued on 8 May (Edict of Worms). From then on Luther's writings were prohibited. No-one was permitted to offer him lodgings, and each citizen was instructed to deliver him into papal hands.
Luther was summoned to hearings or disputations in Augsburg, Heidelberg and Leipzig after he posted his 95 theses condemning the sale of indulgences on 31 October 1517. In particular the Leipzig disputation of 1519 with Johannes Eck, a professor from Ingolstadt, opened up a progressively irreconcilable chasm between Luther's statements and Church tradition, especially when he voiced the opinion during the confrontation that Johannes Hus, burned at the stake 1415 in Constance, had been correct in several of his articles.
The three pamphlets published in 1520 – "To the Christian Nobility of the German Nation Concerning the Reform of the Christian Estate", "On the Freedom of a Christian" and "On the Babylonian Captivity of the Church" – aggravated the situation, forcing Rome's hand. Initially the Pope responded by dispatching a Papal bull threatening excommunication, which Luther burned in public before the gates of Wittenberg on 10 December 1520.
The Pope then excommunicated Luther on 3 January 1521. The traditional defenders of the faith had actually anticipated that excommunication would be followed immediately by an Imperial ban, but the imperial potentates and noblemen insisted on hearing Luther before an Imperial Diet. King Charles V summoned the monk to attend the gathering in a letter on 6 March, in which he also assured safe passage to the venue in Worms.
Charles V (1500 – 1558) had ascended to the Habsburg throne as designated successor to the Holy Roman Empire at the tender age of 19, just two years before the 1521 Diet of Worms. Pope Leo X (1475 – 1521) from the House of Medici had endorsed the French King Francis I (1494 - 1547) in the electoral college. Doing justice to his name, the Saxon Elector Frederick the Wise (1462 – 1525) had refrained from putting himself forward for the position. Charles faced the task of reconciling contrary interests to assert his political claim to a pax habsburgica in Europe under the sovereignty of his Empire.
The French crown had designs on a similar regency. The Empire had therefore been at war with France in Upper Italy since 1520. The German rulers, knights and noblemen were demanding greater freedoms from the Empire. The Pope was determined to cling to his power in Italy and Europe, which he would be able to do by controlling who ascended to the throne. . It was held in Bologna in 1530. Charles V had called himself the "Elected Roman Emperor" since 1520. But while the Pope excommunicated Martin Luther as an opponent to his centralised power, Frederick the Wise advocated arbitration proceedings according to imperial law.
Rough estimates suggest that around 7,000 people lived in Worms at the start of the 16th century. Almost twice as many visitors to the Imperial Diet had descended on the city since January 1521. The number of visitors exceeded expectations by far, and it soon became clear that the preliminary planning had been inadequate. Food was expensive and accommodation was hard to find. The Papal Emissary Nuntius Aleander reported loquaciously in his dispatches to Rome on the annoyances and animosity he encountered wherever he went. He wrote: Ninety percent of Germans have adopted the battle cry 'Luther', while the rest are prone to exclaiming 'Death to the Roman court' at least, if not worse. The hostility that Aleander encountered was in stark contrast to Luther's popularity.
Luther had set off on his journey on 2 April, perched atop a two-wheeled wagon drawn by three horses, which the Council of Wittenberg had placed at his disposal. He was accompanied by Kaspar Sturm, the Imperial Herald. Arriving in Oppenheim, friends tried to spirit Luther away to Ebernburg Castle. But despite the grave danger, Luther was determined to continue to Worms, even if the devils awaiting him there might be as legion as the tiles on the roofs. Luther was greeted by a crowd when he entered Worms through Martin's Gate on the morning of Tuesday, 16 April, arriving from the North. The people were just as excited to see him as they were the 21-year-old Charles V.
Luther found lodgings in the Seminary of St John. Over the next ten days, a constant procession of visitors descended on the room that Luther had to share with two other men. Legend has it that they even included two Jews, with whom he is said to have discussed problems of translating from Hebrew into German.
The Bishop's palace where the King was residing was deliberately chosen as the venue for the hearing. It drew a clear line between the 'Luther issue' and the actual affairs of the Imperial Diet, which were negotiated in the town hall and the house 'Zur Münze' (Guildhall). Comprising several wings, the Bishop's palace was built as an annex to the Cathedral. Spanish representatives at the hearing of Luther described the low, cramped room chosen for the hearing on 17 April, as well as the larger chambers to which the proceedings moved on 18 April to accommodate the sizeable audience.
Charles V summoned Luther to the Bishop's palace on 17 April, where he was questioned on his books by the Archbishop of Trier. Dressed in a monk's habit, Luther stood before the King and the Electors in an offnen sal (open dock). Luther had six Doctores from the University of Wittenberg as his amicus curiae. Standing by the door, the infantry commander Georg von Frundsberg is reported to have said: Little monk, it is an arduous path you are taking. Sources agree that the Archbishop asked Luther whether he was the author of the books and writings that appear in his name. Prompted by Hieronymous Schurf, legal counsel to the Saxon Elector, he then read out the titles of the books. Luther admitted in his reply that he was the author of the writings, but that simply recanting them would not be so simple, indicating that it would be a question of eternal salvation and asking for a period of reflection. In his response, the Archbishop made Luther aware of the consequences that refusing to recant would bring, granting him a period of reflection until the following day.
Luther was collected at around 4 pm on 18 April. He was forced to wait for two hours as the king was otherwise occupied. Then he entered the halls, lit by torches, to stand again before Charles V. Von der Ecken asked Luther in Latin and German whether he would recant his writings.
Speaking without a script, the reformer responded initially in German, but was then instructed to proceed with his detailed answer in Latin. He assigned his books to three categories. Even his opponents would find some of his books useful, he claimed, adding that he would be loath to be alone in condemning the truth. The second category of his books, he said, are based on the Bible and even canon law and would merely express the objections addressed by the German nation to the Pope. Recanting these works would strengthen Roman tyranny. Then he asserted that the third category of his writings dealt with individual persons. Here he conceded that his wordings had been more caustic than might befit his profession and religion. But that he would not recant them. So prompted again, he provides a brief statement:
If, then, I am not convinced by proof from Holy Scripture, or by cogent reasons, if I am not satisfied by the very text I have cited, and if my judgement is not in this way brought into subjection to God’s word. I neither can nor will retract anything; for it can not be right for a Christian to speak against his country. So help me God. Amen. The following words were added retrospectively: Here I stand, I can do no other.
These words lent Luther's appearance before the Imperial Diet a historical significance if one considers that the appeal to reason ('cogent reasons') and personal conscience based on written testimony – in clear defiance of the authority of the Church – points ahead to a time that would not begin until the onset of the Enlightenment. At this point the King stopped the proceedings, and the chambers descended into turmoil. Luther was accompanied out by his supporters, and he is said to have raised his arms and exclaimed: I am finished!
In a written declaration penned the following day, the King invoked his lineage from a noble family and defenders of traditional beliefs, stating that an individual monk could not be right in contradicting one and a half thousand years of ecclesiastical tradition: "It is certain that an individual brother shall err in his opinion if this should be in opposition to all of Christianity as it has been taught for more than a thousand years and is taught until this day, as otherwise all of Christendom must err today and heretofore have erred as well." He could no longer be dissuaded from issuing an Imperial ban on Luther. The Edict of Worms was therefore issued in this form on 8 May and then published on 26 May. Further discussions with Luther before his departure on 26 April did not produce any results. So Luther set off again on 26 April, escorted only by two companions, and was attacked near Altenstein Castle. The attack was a ruse carried out on the instructions of Elector Frederick, who arranged for Luther to be hidden in Wartburg Castle.