You might consider the different roles within the Church played by various pilgrims on the trip to Canterbury. Which characters does Chaucer portray favorably; which does he portray negatively? Which characters live up to the standards of holiness or piety that "should" go along with a role in the Church, and which ones fall very short of that?

Then ask yourself, are these characters individual characters, or do they represent that entire group within the Church? How might you argue your viewpoint of that one way or another, based on the text itself and what you find out about medieval literature from reading an introductory work like the Cambridge Companion to Chaucer or some "Introduction to Medieval Literature" (pick one; if they talk about England, they talk about Chaucer) from your library?