He joined the debate on Christian doctrine in his Repressing of Over Mich Wyting [blaming] the Clergie, 1449, and Book of Faith, 1456.

In attacking the Lollards, Pecock put forward the following religious views: he asserted that the Scriptures were not the only standard of right and wrong; he questioned some of the articles of the creed and the infallibility of the Church; he wished "bi cleer witte drawe men into consente of trewe feith otherwise than bi fire and swerd or hangement" and in general he exalted the authority of reason.

Pecock, who has been called "the most prolific English theologian of the 15th century",[5] was then forced to resign his bishopric in January 1459,[3] and was removed to Thorney Abbey in Cambridgeshire, where he doubtless remained[citation needed] until his death about 1461.

[3] The bishop's chief work is the famous Represser of over-much weeting [blaming] of the Clergie, which was issued c. 1449–1455.

In addition to its great importance in the history of the Lollard movement the Represser has an exceptional interest as a model of the English of the time, Pecock being one of the first writers to use the vernacular.