As a teacher responsible for reading and interpreting the Scriptures, he noticed that certain practices and beliefs of the church were not in accordance with the message of Jesus. He started to denounce them in public, but he was not given attention by the authorities.

Excluded from the church, he kept on protesting and proposing changes in the way things were done and said, both in the worship service and in collective and individual life. Thus he became one of the foremost reformers of the church, something which came about more by circumstances than by his own will.

In order to combat errors and propose manifestations of faith and piety according to the Gospel, he produced polemic writings, both didactic and pastoral, reformulated the order of the worship service, composed hymns and, along with colleagues from the University, translated the New Testament to begin with, and then the whole Bible to the language of the people. His works, continually reprinted and translated, make up an invaluable treasure for all those seeking to understand the identity and vocation of the Christian Church.