The Pardoner is characterized as an individual lacking moral scruples during the Prologue. As a member of the Roman Catholic church, he is expected to embody the tenets of this faith; however, the irony is established by the Pardoner's confession: he crafts fake relics in order to exact a pretty penny from the church congregation and pockets the indulgences that were meant to buy spiritual salvation. This is a flagrant disregard for the Christian teachings, since he is endorsing greed and dishonesty.
Important to note is the way in which the Pardoner is physically depicted. Being compared to a "gelding" or "mare" creates a unique characterization of the Pardoner. Gelding referred to a eunuch, who is a castrated, pre-pubescent male; this would explain the pardoner's high-pitched voice and lack of facial hair. The "mare" would be someone who was effeminate, potentially hermaphroditic or homosexual. In either interpretation, the Pardoner is crafted as aberrant sexually. This sexual deficiency would align with the Pardoner's moral deficiency, as it’s believed that the outward mirrored the soul. Therefore, through the physical depiction of the Pardoner, Chaucer furthers the base characterization of the Pardoner.
The actual tale indicts greed and jealousy; it reinforces Church teachings. However, the fact that the tale ends with the Pardoner trying to sell fakes after his confession indicates that the words of the Pardoner do not match his true self.