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.

He and his friends were thrown into a state of great alarm by this unexpected step. On the one hand, were he to submit and to acknowledge that he had been in error his reputation would be shattered, the Augustinians would feel themselves disgraced, and the University of Wittenberg would lose caste in the estimation of educated Germans. On the other hand, if he adopted the bold policy of refusing to yield to the papal entreaties he was in danger of being denounced publicly as a heretic. In this difficult situation his friends determined to invoke the protection of the Elector Frederick of Saxony, the founder and patron of Wittenberg University. Alarmed by the danger that threatened this institution from the removal or excommunication of one of its most popular professors, and anxious to gain time, Frederick requested the Pope to refer the matter for decision to some German bishop or to a neutral university. In reply to this request Leo X. appointed Cardinal Cajetan, papal legate in Germany, to hold an inquiry (23 Aug., 1518). Luther, having armed himself with a safe conduct, went to Augsburg to meet the papal representative, who received him very kindly, and exhorted him to withdraw his statements and submit. Luther endeavoured to induce the cardinal to enter into a discussion on the questions in dispute, but the latter did not allow himself to be drawn into a disputation. Finally, Luther refused to submit, though, at the same time, he declared solemnly that he wished unsaid and unwritten what he had said or written against the Roman Church. A few days later he fled from Augsburg after having drawn up a formal appeal "from the Pope ill-informed to the Pope well-informed," while the cardinal, disappointed by the failure of his efforts, turned to the Elector of Saxony for help against the rebellious monk. But the latter, deceived by the recommendations forwarded on Luther's behalf by his own superior, Staupitz, yielded to the entreaties of Spalatin, the court chaplain, and of the professors of Wittenberg, and declined to take any steps to compel Luther to submit. Fearful, however, lest his patron might not be able to shield him from the censures of Rome, Luther determined to anticipate the expected condemnation by issuing an appeal to a future General Council (28 Nov., 1518).