What did Roger Williams wanted to create a barrier between to prevent Christian contamination

Roger Williams and his followers settled on Narragansett Bay, where they purchased land from the Narragansett Indians and established a new colony governed by the principles of religious liberty and separation of church and state. Rhode Island became a haven for Baptists, Quakers, Jews and other religious minorities. Nearly a century after his death, Williams’ notion of a “wall of separation” between church and state inspired the founders of the United States, who incorporated it into the U.S. Constitution and Bill of Rights.