Although the Puritans are often depicted as seeking freedom of conscience, that is misleading. They really wanted freedom from error - in other words liberty from false religion imposed by Charles and his advisers in order to foster true religion according to their Calvinist standards. Not only Catholics but also Anglicans were excluded from the colony: two of the first settlers, the Browne brothers, were shipped back home because they wanted to worship according to the Book of Common Prayer.
D. Reynolds, America: Empire of Liberty (2009), 34