Since there are many religious figures in The Canterbury Tales, we would expect religion and its attendant subjects to be a common topic, and it is. The biggest question about holiness in the Tales is whether outward shows of piety, like those practiced by the Summoner and the Pardoner, are enough to constitute true holiness. This question is not as cut-and-dried as it might appear, since the medieval church endorsed the value of outward, physical shows of piety like the very pilgrimage upon which these characters have embarked. But characters like the Parson and the Plowman suggest that something more might be required for true holiness, and that the "something more" might not be as fussy and complicated as pilgrims like the Prioress, Pardoner, or Summoner would have us believe.
In suggesting that something more than an outward physical demonstration is necessary for true piety, The Canterbury Tales complicate our understanding of pilgrimage.
The portrayal of the commoditization of spiritual goods like pardons and repentance in The Canterbury Tales questions the extent to which the physical and material should play a part in the spiritual life.