How does Hawthorne use irony with regard to Dimmesdale's sin?I am writing an essay on The Scarlet Letter and I need some help figuring out why...

At the end of The Scarlet Letter,
Nathaniel Hawthorne explicitly states the theme of his seminal
novel:

Be
true!  Be true! Be true!  Show to the world  your innermost
self....

Hawthorne's
narrative, which is an indictment of the consequences to the soul of the stern ideology
of Puritanism contrasts the character of Hester Prynne, whose sin is made public to
the character of the Reverend Arthur Dimmesdale, whose sin is secret.  The irony of
Dimmesdale's character is that it is the truth of his sin that he hides which makes him
revered in his community; it is the truth of his secret sin which he tries to confess
before his congregation which causes him to be perceived as an almost ethereal model of
purity.  And, yet, most ironically, it because of the secretiveness of his sin that
Dimmesdale is tortured and ultimately destroyed as his guilt ravages both his body and
his soul. 

Unlike Dimmesdale, who deteriorates as the
narrative progresses, the publicly scorned Hester Prynne adjusts to her life and
performs good deeds, aiding the sick and comforting the dying.  She is an exemplary
mother, as well.   While she has suffered and lost her beauty, Hester still has a
productive life through her performance of good deeds. This example of Hester's
repentance and acquiring goodness through acts of charity is counter to the
Calvinistic/Puritan belief that good deeds do not have value; it is faith alone that
will admit one to heaven.

And, in Puritanism since some are
among the "elect" and some among the "damned," Dimmesdale and others who sin must keep
their transgressions secret, living a life of hypocrisy.  However, as the reader
perceives from the character of Arthur Dimmesdale, this life of "secret sin" is fatal
and tears at the very fiber of the soul as one must fear being found out and one must
hide guilt.  Thus, with Hawthorne's theme that the ideology of Puritanism is one that
forces its believers to be false, he decries the stringent beliefs of Puritanism through
his use of irony with the character of the Reverend Dimmesdale.  For, in its severity to
make believers adhere to spiritual laws, Puritanism ironically causes them to hide their
sins and be hypocritical since no human can be faultless.