As a result of this controversy between Eck and Carlstadt it was arranged that a public disputation should be held at Leipzig (27 June-15 July, 1519). The Catholic teaching was to be defended by Eck against his two opponents, Luther and Carlstadt. A hall in the castle of Pleissenburg was placed at the disposal of the disputants by Duke George of Saxony, who was a convinced Catholic himself, and who believed that the disputation might be the means of removing many doubts and misunderstandings. The acts of the disputation were to be drawn up and forwarded to the Universities of Paris and Erfurt for their decision. When it became known throughout Germany that a meeting had been arranged between Eck and his two principal opponents, the excitement, especially in the learned circles, became intense, and so great was the rush of scholars from all parts of the country to witness the encounter, that the immense hall was packed with an eager and attentive audience when Eck and Carlstadt entered the pulpits that had been prepared for them.
Few men in Germany, or outside it, were more fitted to hold their own in such a disputation than the distinguished Vice-Chancellor of Ingolstadt. He was a man of imposing appearance, gifted with a clear and pleasing voice and good memory, even tempered and ready, quick to detect the weak points of his adversaries, and keenly alert to their damaging concessions and admissions. The first point to be debated between him and Carlstadt was the question of Grace and Free Will.
Carlstadt was at last obliged to concede that the human will was active at least to the extent of co-operating or of not co-operating with divine Grace, a concession that was opposed entirely to the thesis he had undertaken to sustain. Luther, alarmed by the discomfiture of his colleague, determined to enter the lists at once on the question of the primacy of the Roman See. He was not, however, more successful than Carlstadt. Eck, taking advantage of Luther's irascible temperament and his exaggerations of speech, forced him step by step to put aside as worthless interpretations given by the early Fathers to certain passages of Scripture, and to reject the authority and infallibility of General Councils. Such a line of arguments, opposed as it was to the teaching and beliefs of the Church, roused the opposition of the audience, and served to open the eyes of Duke George to the real nature of Luther's movement. Annoyed by his own defeat and by the attentions and applause lavished upon his rival by the people of Leipzig, Luther left the city in disgust. The disputation undoubtedly did good in so far as it made clear to all the position of the two parties, and succeeded in holding Duke George of Saxony and the city of Leipzig loyal to the Church; but it also did much harm by giving Luther the notoriety that he was so anxious to obtain, and by winning to his side Philip Melanchthon, who was destined to be in after life his ablest lieutenant. Both sides, as is usual in such contests, claimed the victory. The Universities of Cologne and Louvain condemned Luther immediately, as did also Paris in 1521, but as far as can be known Erfurt pronounced no decision on the questions submitted.
Meanwhile what was the attitude of the authorities in Rome towards Luther's movement. Leo X., having learned something of the turmoil created in Germany by Luther's theses and sermons, requested the vicar-general of the Augustinians to induce his rebellious subject to recall his teaching, or, at least, to keep silent. The vicar wrote to the principal, Staupitz, but, as the latter was one of those who had encouraged Luther to take the steps he had taken, very little was done to secure peace. Luther was, however, induced to write a most submissive letter to the Pope in which he begged for an investigation, pledging himself at the same time to accept the decision of Leo X. as the decision of Christ (30th May, 1518).[14] Not satisfied with the course of events, and alarmed by the reports forwarded to him from Germany, the Pope appointed a commission to examine the whole question, the result of which commission was that Luther was summoned to submit at once or to appear at Rome to defend himself within sixty days.