In Oxford he was allowed to hold a disputation with some learned doctors on the rival merits of the Copernican and so-called Aristotelian systems of the universe, and, according to his own report, had an easy victory.
After a public disputation in which the Catholics were weakly represented, and a popular demonstration in favour of the new doctrines, the council of Geneva rather reluctantly sanctioned the abolition of the Mass.
In 633 he was one of the party of Sophronius of Jerusalem (the chief original opponent of the Monothelites) at the council of Alexandria; and in 645 he was again in Africa, when he held in presence of the governor and a number of bishops the disputation with Pyrrhus, the deposed and banished patriarch of Constantinople, which resulted in the (temporary) conversion of his interlocutor to the Dyothelite view.
After a brief stay in the grammar school of Colmar he went to Strassburg in 1651, where he devoted himself to the study of philology, history and philosophy, and won his degree of master (1653) by a disputation against the philosophy of Hobbes.
Lecturing on Isaiah he condemned current ecclesiastical abuses, and in a public disputation (loth of August 1523) was so successful that Erasmus writing to Zurich said "Oecolampadius has the upper hand amongst us."