Missae christianorum contra Luterana[m] missandi formula[m] Assertio.
Dresden: [Emserpresse?], 1524. A-E4, F2./ Errata on p. . First edition. Item #819
At first Emser was on the side of the reformers, but like his patron he desired a practical reformation of the clergy without any doctrinal breach with the past or the church; and his liberal sympathies were mainly humanistic, like those of Erasmus and others who parted company with Luther after 1519. As late as that year Luther referred to him as "Emser noster," but the Leipzig Debate in that year completed the breach between them.
Emser warned his Bohemian friends against Luther, and Luther retorted with an attack on Emser which outdid in scurrility all his polemical writings. Emser, who was further embittered by an attack of the Leipzig students, imitated Luther's violence, and asserted that Luther's whole crusade originated in nothing more than enmity to the Dominicans, Luther's reply was to burn Emser's books along with Leo X's bull of excommunication.
Emser next, in 1521, published an attack on Luther's Appeal to the German Nobility, and eight works followed from his pen in the controversy, in which he defended the Roman doctrine of the Mass and the primacy of the pope. At Duke George's instance he prepared, in 1523, a German translation of Henry VIII's Assertio Septem Sacramentorum contra Lutherum, and criticized Luther's New Testament. He also entered into a controversy with Zwingli. He took an active part in organizing a reformed Roman Catholic Church in Germany, and in 1527 published a German version of the New Testament as a counterblast to Luther's. He died on the 8th of November in that year and was buried at Dresden.
Emser was a vigorous controversialist, and next to Eck the most eminent of the German divines who stood by the old church. But he was hardly a great scholar; the errors he detected in Luther's New Testament were for the most part legitimate variations from the Vulgate, and his own version is merely Luther's adapted to Vulgate requirements.
Emser's crest was a goat's head and Luther delighted in calling him "Bock-Emser" and "Ægocero" Luther, in his several dealings with Emser, called him a goat. Indeed, if you want to read something fun, read Luther’s utterly ‘dripping with pure contempt and loathing’ for Emser book titled Answer to the Hyperchristian, Hyperspiritual, and Hyperlearned Book by Goat Emser in Leipzig—Including Some Thoughts Regarding His Companion, the Fool Murner.