By the spring of 1518 Luther had published a second booklet titled A Sermon on Indulgence and Grace. Unlike the 95 theses which were written in Latin, this second booklet which was an exposition of many of the principles and arguments highlighted in the theses was written in German vernacular making it easily accessible to all classes of people. A Sermon on Indulgence and Grace was reprinted four times in 1518 alone and each printing generated at least a thousand copies of the book.

Whereas Rome had not taken much notice of Luther's initial theses, this second booklet grabbed their attention. Largely because it was so accessible to the common people but also because it was popular and had the potential to stir up trouble. While Luther had initially set out to challenge the doctrine of indulgences, the rapidly escalating list of challenges associated with that single charge encompassed issues that threatened to shake the very foundations of the church.

In challenging the doctrine of indulgences Luther argued for the supremacy of Scripture, questioned the authority of the Pope, and challenged the importance and role of the sacraments in relation to salvation. Each of these arguments, by themselves, would have been enough to bring down the pillars of the church, together they were almost nuclear in their potential reach and impact.

By August of 1518, Pope Leo X commissioned a Dominican Friar by the name of Sylvester Perierias to write a denunciation against Luther's 95 theses. Perierias' arguments led to a single conclusion; to challenge the authority of the church and the Pope in such a manner as Luther had done made him nothing more than a heretic. The unspoken conclusion of this statement was obvious; everyone knew what the church did to heretics.

Perierias concluded his polemic with a summons; Luther was to appear in Rome, within 60 days of receiving the denunciation to answer to the charges of heresy that had been brought against him. This was, of course, an invitation to walk on the sharp edge of a long sword. The last time a heretic had been summoned to Rome before the Pope and the Emperor to answer to the charge of heresy, he had been imprisoned and burned. Luther did not want to end up like Jan Hus.

In a shrewd political move that likely saved Luther's life, Prince Frederick, his patron and the Elector of Saxony, petitioned Rome for an alternate venue for Luther's hearing. He suggested that Luther be questioned on German soil, at the Diet of Augsburg by the Papel Legate, Cardinal Thomas Cajetan. The Pope agreed to the request and between the 12th and 14th of October 1518, Cardinal Cajetan interviewed Luther three times.

As far as Cajetan and the Pope were concerned Luther only needed to utter a single word; Revocco (I recant). Luther refused. Cajetan then attempted to debate with him, using Papal pronouncements regarding salvation and merit as a basis for his arguments. Luther refused to accept these, stating that unless Cajetan could produce proof from Scripture to back up his arguments none of them were valid.

The two were deadlocked and, in desperation, Luther appealed to the Pope for a hearing. Cajetan dismissed him in frustration and defeat. There were rumors that guards at the gate had been given instructions to arrest Luther should he attempt to leave Augsburg but, with Johann Von Staupitz's help, Luther managed to find a horse and escape the city in the dead of night. Luther arrived back home in Wittenburg having traveled on back roads via Nurenburg, on the 30th of October. He was unscathed but knew the weight of a noose now dangled just above his head.