did Roger Williams believed in the separation of Church and State ?
Roger Williams believed that there should be freedom of religion and the separation of church and state. It is because of this that he was banished from Massachusetts Bay Colony. He later on went and settled in Rhode Island among the Narragansett Indians and then founded destiny. You can check out http://americanhistory.about.com/b/2008/10/09/roger-williams-and-the-separation-of-church-and-state.htm for more information.
If you mean the pianist, maybe. If you mean the theologian, perhaps not.