Roger Williams is important because he was the founder of the Rhode Island Colony. He also was one of the early proponents of religious freedom and tolerance in British North America.
Roger Williams came to Boston in 1631 but soon had a falling out with the Puritan leadership in Massachusetts. He vehemently disagreed with their theocratic practices that so closely aligned church and state. He also criticized the notion of royal charters. He argued that land could only be legitimately held by European settlers if it had been purchased fairly from the Native Americans who had lived there.
These subversive views got Roger Williams banished from the Massachusetts Bay Colony in 1636. He then headed south into what was then considered the wilderness. There, he bought land from the Narragansett tribe and founded his own colony called Rhode Island. He was able to obtain an official charter for his colony from the English crown, which went into effect in 1663. This small colony was founded on the notion of religious tolerance and became a refuge for Quakers, Anabaptists, Lutherans, and others who were unwelcome in the more Puritan colonies elsewhere in New England.
Even long after the death of Roger Williams in 1683, Rhode Island continued its tradition of religious acceptance and tolerance. Throughout the colonial period, it was a haven for marginalized religious minorities such as Jews and Catholics. In fact, representatives from Rhode Island at the constitutional convention were some of the most vehement supporters of the First Amendment, which guarantees the separation of church and state. This is all thanks to the legacy of Rhode Island's founder, Roger Williams.