Redemption is a personal affair.
This is one way I read the novel. Hester's redemption, though publically enforced in terms of penance, is actualized privately. This is how it has to be when the crime is also personal, as is the guilt brought on by Hester's transgression.
As much the community wishes to govern individual's internal lives, there is no way for healing and change to take place publically when the entity being changed and healed is a person with a deep internal life.
In Chapter XX, Hawthorne writes,
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 the true.
The sanctimonious hypocrisy is a motif that runs throughout the narrative of The Scarlet Letter. For example, Governor Bellingham, who is the leader of the Puritan community, has articles of war (armor) in his elaborated designed house with stained glass windows and other ornate structures--contrary to the plainness and simple attributes demanded by Puritanism. His own sister is a witch who attends the black mass in the forest.
So, in the final chapter, Hawthorne openly declares his theme and moral:
Be true! Be true! Be true! Show freely to the world, if not your worst, yet some trait whereby the worst can be inferred!
This moral is underscored in the characters of Hester and the Reverend Arthur Dimmesdale as it is Hester who survives and gains a place in her community, but Dimmesdale is destroyed by the guilt of his secret sin.
I think Hawthorne's theme in The Scarlet Letter has to do with the value of the sincere individual vs. the oppressive nature of social structures that exist to serve their own perpetuation. Hester had a purity of character that could not be destroyed by the misguided and thoughtless portion of the Puritan society in which she lived.
Hawthorne's central objective was the denunciation of Puritan religious practices (who can blame him?). One succinct statement of the overarching theme behind all the minor themes that emerge might be presented as this: The practice of Puritan values results in false destruction of life, human worth and human dignity since it is human to err though divine to forgive.
Most of the universal themes apply: love, guilt and innocence, individual versus society. For individual versus society, Hester is suffering under the weight of her oppressive society’s unrealistic expectations. This causes her great pain for the rest of her life.