In the setting of "The Scarlet Letter" -- the Massachusetts Bay Colony -- "religion and law were almost identical." The puritanical code informed the civil laws, making sins and crimes synonymous. As such, the sin of adultery was also a crime, and the punishment was biblical instead of secular. The Puritans were a 16th and 17th century sect of Protestant Christians influenced by Calvinism.
Prynne was punished for the crime of adultery with public shaming. In addition to being forced to stand on the scaffold with the pillory, designed "to be as effectual an agent, in the promotion of good citizenship, as ever was the guillotine among the terrorists of France," she was also forced to wear a scarlet A, for adultery, on the breast of her dress until her death. This action was seen as a more-merciful punishment -- the prescribed sentence, in biblical law, being death.
When Prynne was first presented to the town for her punishment, one of the townswomen said, "This woman has brought shame upon us all," implying that the deeds of the individual reflected on the society as a whole. The recurring motif of the town versus the forest illustrated the dichotomy of individuality and society. The town represented the order of civilization while the forest was a place where Prynne and Dimmesdale were free to act as they wished. Prynne's home, on the outermost edge of town, was a symbolic waypoint, standing at the bounds of civilization and man-made laws and the forest and the laws of nature. Both Prynne and Dimmesdale remained in the town -- Prynne because she did not wish to allow civilization to drive her away and Dimmesdale because he was beaten down by it.
Early in the novel, the townswomen described the magistrates as overly merciful for choosing to shame Prynne where the women would have put her to death. Over the years, Prynne became a figure of strength in the community for her unflagging work in support of the poor and the sick. Indeed, Prynne was a symbol of womanly passion and emotion. This stood in stark contrast to the town elders, who were "fortified ... by an iron framework of reasoning" as "men of rank, on whom their eminent position imposed the guardianship of the public morals."