On May 26, 1647, the Massachusetts Bay General Court officially passed a law banning Jesuit Catholic priests from the Bay Colony.
In part, the law was passed because Puritans insisted upon purifying themselves and protecting the Protestant faith from Catholicism. The Puritans has originally broken away from the Church of England because it hadn't fully extricated itself from Catholic practices such as holy water, crucifixes and stained glass windows.
The other part was political: the Puritans were worried about the incursion of the French from Canada, who were encroaching on Maine, which was then part of the Massachusetts Bay colony. The French Jesuits were converting Indians to Catholicism, raising the scenario that the French could induce the Indians to help defeat the Protestant New Englanders as the two European powers sought to carve out territories in America.
It was "the only penal law against the presence of priests to be enacted in 17th century New England," according to historian Arthur Reilly, in his scholarly book, Catholicism in New England to 1788.
"To ensure observance of this law, heavy penalties were annexed," writes Reilly. "One suspected of being a member of the Jesuits or an ecclesiastic subject to the See of Rome was to be tried before a magistrate. If suspicion remained and could be proved, the Court of Assistants was to banish or otherwise proceed against him. Anyone, so banished, taken a second time, would be put to death after lawful trial and conviction."
The anti-Catholic sentiment in New England lasted for centuries, even though Catholics were eventually accepted, starting with a public mass being celebrated in Boston in 1788. But the negative reception of German and Irish Catholics in 19th century Boston demonstrated that the Puritan prejudice still lingered with a vengeance.
Read more about the Jesuit ban at MassMoments.