Based upon the above context, Chaucer chooses the word paragon to show irony and humor in referring to the Pardoner.
The word is used to refer to a highly respected member of the clergy, but the Pardoner is not one, as being described by his actions. The Pardoner earns money by playing with people’s faith, he sells indulgences and false relics. Chaucer describes the Pardoner as selfish and deceptive, someone who only worries about his personal motives.
Religion is a general theme in the Pardoner’s prologue, Chaucer includes his views and thoughts on religion in a subtle way, as it was still a time when someone couldn’t write about certain things. The Pardoner entertain his audience with his wit and sense of humor, mocking the church and other institutions surrounding it, going against everything he is supposed to be.