What is the significance in the story of the continual reference to pigs and hogs, and how are they a metaphor enhancing the theme of "Revelation"?

Pigs, hogs, and even warthogs are used symbolically in
various ways in Flannery O’Connor’s short story titled “Revelation.” Among those ways
are the following:

• They function as symbols of
  pride.  Mrs. Turpin takes pride in raising pigs, just as she takes pride in so many
  other details of her life and personality. She is a fairly prosperous pig-farmer and is
  up-to-date on all the latest innovations in the field (such as concrete pig-pins).
  O’Connor, who continually mocks pride in her stories, must have enjoyed the humor of
  creating a person who took pride, of all things, in pigs. Since pigs have usually been
  regarded as among the least appealing of animals (at least until they become ham and
  bacon), O’Connor would have enjoyed the extreme irony of making a human being proud of
  her association with pigs.

• Whereas
  Mrs. Turpin is proud of her pigs, she is rather judgmental and condescending toward most
  of the other people around her (except her beloved husband, Claude, whose name links him
  with earthy simplicity). Mrs. Turpin often treats other people as if they were pigs, and
  she often regards her pigs as prized possessions.  Indeed, it is because they are in
  fact possessions, which can be used, that they are so important to
  her.

• Pigs are often thought to have
  voracious appetites, to spend much of their time wallowing in mud or other filth, and to
  appear (in the words of the Oxford English Dictionary) “boorish,
  coarse, [and] obstinate.” For all these reasons and others, they can be symbolically
  (and literally) associated with the world and with such worldly qualities as greed,
  gluttony, and laziness. It isn’t as if Mrs. Turpin is proud of raising horses or dogs
  (generally considered more attractive animals); she is proud of raising
  pigs.

• Part of O’Connor’s “point,” in
  this story, is that human beings have little reason to be particularly proud of
  themselves. Seen from a certain point of view, we are all pigs: we are all
  self-indulgent, greedy, spiritually lazy, and soiled by sin. Indeed, when real pigs
  actually do appear in this story, they seem far more attractive than some of the human
  beings we have witnessed, and they definitely seem more attractive than the ugly, absurd
  thoughts percolating in Mrs. Turpin’s highly prejudiced mind. Thus, near the end of the
  story, O’Connor describes a bunch of baby pigs gathered around their huge
  mother:

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They had settled in one corner all around the old
sow who was grunting softly. A red glow [from the sun setting] suffused them. They
appeared to pant with a secret
life.

In phrasing such as
this, O’Connor (in an added irony) suggests that the pigs are behaving more naturally,
more in accord with how God created them to be, than many of the humans (and especially
Mrs. Turpin) have behaved. In a further example of O'Connor's irony, there is actually
something beautiful about this depiction of the pig and her piglets (actually a hog and
her shoats).

Although pigs, hogs, and warthogs function
symbolically in various other ways in the story, the functions just outlined are hard to
deny.