Chaucer plays with the concept in religion in The Canterbury tales. He shows that many clergymen are corrupt, both by the stories that the pilgrims tell and the pilgrims themselves, for example the Summoner and Pardoner. In fact, most of the characters of The Canterbury Tales have a loose interpretation, or no interpretation, of morality as told by the Bible. The Sailor, the Reeve, and the Miller tell racy bar-room stories, and the Wife of Bath speaks of her many husbands, and many years of marital experience, in a way that puts quite a different interpretation on religious and moral beliefs of her day.
Characters that keep to a strict moral compass are few; the Prioress and her company are the most notable examples. However, even they have an altered view of morality. In the Prioress' Tale, she exalts a young boy as a martyr, but condemns the entire Jewish Race in the same breath. Historically, this was an accepted thing for Christians to do, but Chaucer puts the story there as a subtle attack on the intolerance of Christianity.