At this time, in association with the keen humanists Conrad Mutian, Crotus Rubeanus and Eoban Hess, he was of sceptical tendency; moving to Wittenberg in 1519, he became evangelical under the teaching of Melanchthon and the preaching of Luther.
The reversion to the Roman communion of his old friend Crotus led to his mordant Responsio amici (1532, anon.) to the Apologia (1531) of Crotus.
Johann Reuchlin, a well-known scholar, who had been charged by the Dominicans with heresy, not only received the support of the newer type of scholars, who wrote him encouraging letters which he published under the title Epistolae clarorum virorum, but this collection suggested to Crotus Rubianus and Ulrich von Hutten one of the most successful satires of the ages, the Epistolae obscurorum virorum.
Like Italian men of letters, these pioneers of humanism gave a classic turn to their patronymics; unfamiliar names, Crotus Rubeanus and Pierius Graecus, Capnion and Lupambulus Ganymedes, Oecolampadius and Melanchthon, resounded on the Rhine.