He was a Doctor of theology of the University of Paris, and was receptive to the ideas of the Protestant Reformation. However, he entered into open confrontation with John Calvin, the central figure of French Protestantism. In a theological dispute, Caroli accused Calvin and Guillaume Farel of Arianism and Sabellianism.
Caroli was a teacher of theology in Paris in 1520. There he had been under the influence of a leader of the humanists, Jacques Faber Stapulensis (Lefèvre d'Etaples), and belonged to the group supporting the return of the bishop Guillaume Briçonnet de Meaux. He was professor in the Sorbonne for some years. However, in 1525, his theses on the Epistles of Paul had unleashed an attack on him by of the censorship, and he was expelled from the Sorbonne.
The sister of the king, Margaret of Angoulême, called on his services and gave him in 1530 a position in a parish in Alençon. In 1534, the Protestants were persecuted. Like Calvin, Caroli was a fugitive. He went to Geneva in 1535 and joined Farel there. Shortly afterwards he went to Basel, where he studied Hebrew and became a friend of Simon Grynaeus and Oswald Myconius. In 1536 he took part in the great theological dispute in Lausanne, supporting the reformation cause.
In consequence of his participation in the dispute, he gained recognition in Bern, which nominated him as the first pastor of Lausanne. He entered then into conflict with Calvin and Farel, having run away from Lausanne, leaving his wife and abandoning the Protestant faith. The government of Bern banished Caroli in 1537. Caroli moved to Montpellier. Expelled from France, he went in 1539 to Neuenberg, where he made peace with the Swiss reformers, without however receiving any position.
- http://www.hls-dhs-dss.ch/textes/f/F11070.php (French language)