As they began to pay attention to the corruption pervading the English government, John Winthrop and his fellow Puritans got swept up in events happening far from Winthrop's Groton estate. The Puritan movement found itself in a position where it thought it stood as the last line of defense against the wickedness of English culture. While their preachers condemned the corruption from the pulpit, it was left to the laymen to save England where they could. Winthrop and other Puritans who served as justices began enforcing increasingly strict interpretations of the law to punish wrongdoers who came in front of the court. Likewise, Puritan members of Parliament–who were at least a loud minority if not an outright majority–began passing harsh laws to try and clean up society; Winthrop himself helped to draft a bill against drunkenness in the late 1620s. Parliament had made progress under Queen Elizabeth I establishing itself as a legitimate means of governance, progress which had been continued under Elizabeth's successor, James I.
However the entire situation began to change for the worse in 1625 when James I died and was replaced by by his son, Charles I. When Parliament, which controlled fiscal policy in England, refused to grant Charles the money he demanded to run his programs, he dissolved the body. When it later reconvened, an Anglican bishop began the session with a sermon on obedience and service to one's king. However, the new Parliament was hardly more cooperative than the last, so Charles sent it home and set about raising money using unconventional means. He announced a mandatory loan for English citizens and went about collecting it just as if Parliament had levied a new tax. Many Puritans, sensing the new king's evil side, refused to pay, and the king's forces arrested two of two of Winthrop's close friends and sent them to jail.
Even more troubling for the Puritans than Charles's new fiscal policies was the sharp change in religious feelings in England. For one, Charles had married a Catholic–opening himself up to charges that he was treating the religion leniently–and he had continued a trend started by James I called Arminianism. Under the new belief, a person could be saved solely through his or her own faith and righteous actions, thereby disavowing the Puritan ideal of predestination. In fact, Charles brought the Arminians back to the pulpits (they had been banned from preaching under Elizabeth) to voice support for his new spending and to preach obedience to the king. Those in the Anglican Church who opposed the king's moves quickly found themselves removed from power and replaced by Arminians.
Parliament tried to fight back, demanding an end to the unfair regal taxation and an end to the heresy spreading in the church. It passed a resolution stating that anyone who preached Arminianism should be considered an enemy of the state, but Charles remained more powerful than the members of Parliament. He dissolved the body for a second time and made it clear that there would be no third Parliament.
Winthrop knew that the Puritans' efforts to fight the king would have little standing before God, who would consider them just as guilty of sin as Charles. As justice of the peace and a lawyer in the court of wards and liveries, he had played a small role in the corruption of the government. The dire situation demanded radical action–a second Protestant Reformation of sorts like the one a century before when Henry VIII had ended England's affiliation with the Catholic Church. The growing band of separatists–those who disavowed even the Anglican Church–began looking for alternatives. Some fled to Holland and the small New England colony of Pilgrims at Plymouth, Massachusetts. Winthrop himself began to wrestle with how he could live "in this world" if "this world" was evil and impure.
His eventual decision to leave England for North America came after hearing about fellow Puritans' plans to found a new colony in New England where the Puritans could practice their religion purely and wait for the day when England needed their help. In 1628, a year before Winthrop had begun thinking about fleeing England, a group of settlers had received a charter from the Council of New England–which controlled all settlements in New England–to found a small colony. The charter allowed them to settle an area extending from three miles south of the Charles River (where present day Boston is located) to three miles north of the Merrimack River. And, in the closing moments of Charles's final Parliament, the group received a royal charter and changed its name to the Massachusetts Bay Company. Winthrop's son, John, Jr., first presented the idea of joining the new settlers to his father. In the spring of 1629, Winthrop began drafting a statement explaining his decision to leave England. In June, during a brief break between court sessions, Winthrop and his wife decided to make the move.