Johann Eck, an ordained priest, has taught…

Johann Eck, an ordained priest, has taught theology at Ingolstadt from 1510.

As early as the spring of 1517, Eck had entered into friendly relations with Martin Luther, who had regarded him as in harmony with his own views, but this illusion was short-lived.

In his Obelisci, Eck attacks Luther's theses, which had been sent to him by Christoph von Scheurl, and accuses him of promoting the "heresy of the Bohemian Brethren", fostering anarchy within the Church and branding him a Hussite.

Luther replies in his Asterisci adversxes obeliseos Eccii, while Andreas Karlstadt defends Luther's views of indulgences and engages in a violent controversy with Eck.

A mutual desire for a public disputation leads to a compact between Eck and Luther by which the former pledges himself to meet Karlstadt in debate at Erfurt or Leipzig, on condition that Luther abstain from all participation in the discussion.

In December 1518, Eck publishes the twelve theses that he is prepared to uphold against Karlstadt, but since they are aimed at Luther rather than at the ostensible opponent, Luther addresses an open letter to Karlstadt, in which he declares himself ready to meet Eck in debate.