Puritans were unrelentingly harsh when it came to sin, guilt, crime, and adultery. Theirs was an especially rigid brand of Calvinism which held that humankind is completely mired in depravity. According to Puritanism, we are all guilty of sin, every last one of us, and it is only by God's freely given grace that can anyone ever be reconciled to him. For Puritans, sin wasn't just something you did; it was the fundamental human condition.
Although there was absolutely nothing an individual believer could do to achieve salvation, Puritans still adhered to a very strict code of conduct. They based their moral norms on a narrow interpretation of Scripture, which among other things, strongly prohibited adultery. Adultery was an especially heinous sin in Puritans' eyes. Though they didn't regard marriage as a sacrament—unlike Catholics—they nonetheless venerated the institution, seeing it as a commitment made under God's ever-watchful eye. Little wonder, then, that Puritans took adultery so seriously.
In keeping with their interpretation of Scripture, Puritans were especially harsh when it came to punishing crime. As far as the Puritans were concerned, they'd formed themselves into a godly community. Therefore, any crime committed in their midst was a crime against the community, and by extension against God himself. The seriousness of such crimes was reflected in the brutal methods of punishment and torture used against those who broke the law. Burnings, hangings, and pressings—a method of torture involving the placing of increasingly heavy weights upon the chest—were all too common in the Puritans' godly community.
One of the core ideas of Puritanism was the belief in Original Sin, that all humans are born condemned to spend eternity in hell. The exceptions were the few elect--those souls that God had chosen at birth to save from hell. This is predestination, the idea that people's fates are decided before birth; there is nothing people can do to change their fate.
The Puritans constructed their society to be a "city upon a hill," or a model of Christian behavior, so they believed they had to punish infractions, whether religious or otherwise, quite harshly. The Puritans believed that any act against God was a heinous crime, and they punished crimes quite severely and publicly. Not attending church on Sunday, for example, could be punished by whipping. Other transgressors were placed in the stocks, where they were subject to public ridicule. The pillory, a post about 15 feet high, was used as punishment for crimes such as arson, beating one's wife, and forgery or cheating. The idea was to shame people into behaving by exposing their sins in public.
Sexual crimes were punished with particular severity; for example, sodomy was often punished by execution. In The Scarlet Letter, Hester Prynne must wear an "A" on her clothing as a badge of shame for having committed adultery. She is also largely shunned from the rest of society. In reality, some Puritans who committed adultery, seen as a grave sin and a violation of the Ten Commandments, were whipped. Some women who committed adultery were executed, as adultery was declared a capital crime in the Massachusetts Bay Colony. Men who committed adultery were often whipped but were not treated as harshly as women who committed this crime. This society, in which people stressed moral perfection, resulted in feelings of guilt as many people worried if they were worthy of God's grace.
The Puritans believed that their church had entered into a covenant with God. In this covenant, they pledged to act correctly in return for God's special favor (on Earth).
Because of this, they saw sin, crime, and adultery as violations of their covenant with God (and the covenants they made with each other to act in accordance with God's will). These things had to be punished by the leaders of the church community so that God would not punish the society as a whole.
The Puritans did not, however, see sin as something that would cause people to be damned. People were damned or saved based on predestination and nothing they could do would change their fate.