While the Reverend Arthur Dimmesdale has committed the sin of adultery, the most grievous offence belongs to the theology of Puritanism which disallows any human foibles, thus forcing people to dissemble and hide their secret sins, and demanding absolute perfection from their religious leaders. Dimmesdale's sin is that he is a man with natural feelings and desires, but these human urges are denied him by the strict Calvinism which allows no imperfection from its "elect."
Puritanism should be on trial, not Arthur Dimmesdale, whom it has imprisoned and whose congregation perceives him to be a saint to the very end--even when he confesses his sin, they forgive him.
Here are good acts performed by the Reverend Dimmesdale (not including his usual ministerial duties):
1. While Hester Prynne stands on the scaffold, Dimmesdale is called upon to ask her with whom she sinned. Bending his head "in silent prayer," he then approaches Hester and speaks to her in such a manner as to communicate that she has his permission to name him:
...thou ...seest the accountabiity under which I labour. If thou feelest it to be for thy soul's peace and thy eartly punishment will thereby be made more effectual ...I charge thee to speak out the name of thy fellow-sinner....(Ch. III)
2. After Hester is summoned to bring her child to the mansion of Governor Bellingham, she is told that she must relinquish her child Pearl because the child is not receiving the proper religious instruction. Hester refuses to allow this action, saying, "God gave me this child...She is my happiness!--she is my torture!" Turning to Rev. Dimmesdale, she asks him to speak for her. He defends Hester as knowing better her child than anyone else would; he adds, "...is there not a quality of awful sacredness in the relation between this mother and this child?" Dimmesdale points to how God saw fit to give Hester this baby despite her sin. "It was meant for a blessing; for the one blessing of her life!" he stresses. He argues that little Pearl will keep Hester from sinning further and will keep her soul alive. (Ch. VIII)
3. Because Rev. Dimmesdale has sinned, he is unlike the other ministers; however, he is able to "express the highest truths through the humblest medium of familiar words and images" because he carries the same burdens as they. It provides "him sympathies so intimate with the sinful brotherhood of mankind" that he is able to move his congregation. "They fancied him the mouth-piece of Heaven's messages of wisdom, and rebuke, and love." (Ch.XI)
4. When Hester and the minister speak privately in the forest, Hester encourages Dimmesdale and points out that the "people reverence thee" for his good deeds. (Ch.XVII)
5. While he stands before the townspeople on Election Day to give his speech, on "the very proudest eminence of superiority...and a reputation of whitest sanctity....apotheosised by worshipping admirers" he mounts the scaffold and tells Hester he must "make haste to take my shame upon me." Before the town, the Reverend Dimmesdale confesses his sin and his hypocrisy of hiding his shame for years. By this act, Dimmesdale who also kisses Pearl, acknowledging her as his child and Hester as his beloved, breaks "a spell" and Pearl, the incarnation of his and Hester's sins, becomes fully human:
...she would grow up amid human joy and sorrow, nor for ever do battle with the world, but be a woman in it.
As he dies he calls to Hester, who has implored that he reveal what he sees; the minister tells her that it is vain to hope that they will meet in the hereafter. But, the crowd is in awe that he has accepted his share of sin with Hester. (Ch. XXIII)