What are the elements that unify the plot of The Scarlet Letter?

As the descendent of Puritans, especially an uncle who was
directly involved in the Salem Witchcraft trials, Nathaniel Hawthorne was most concerned
with Puritanism, its hypocrisy, and the resulting treatment of sin. While all three
major characters of The Scarlet Letter have sinned, the secret sin
of Arthur Dimmesdale is torturous to the soul of its owner, while the sin of violating
the heart of a fellow human being is a corrupting sin for Roger Chillingworth, causing
him the very loss of his humanity rendering him a fiend. Thus, for Hawthorne, the
effects of sin and the treatment of sin by the Puritans in their austerity and hypocrisy
and self-deception is the unifying element of Hawthorne's narrative; it is his main
theme.

Hawthorne concludes his novel by referring to this
theme,

No man,
for any considerable period can wear one face to himself, and another to the multitude,
without finally getting bewildered as to which may be
true.

and by expressing his
moral,

"Be
true!  Be true! Show freely to the world, if not your worst, yet some trait whereby the
worst may be
inferred!"

Because Hester has
"been true," she is forgiven her sin and perceived as an "Angel" and caring member of
the community and can live an authentic existence, whereas Chillingworth and Dimmesdale
must dissemble whenever they encounter any members of the community, and in this
falseness of face, they are ruined.