Banished by his peers for his “strange opinions”, Roger Williams has become an unlikely hero in modern America. As founder of Rhode Island, Williams has a place in the US pantheon, but what has made him famous is his championing of religious liberty. (As Gaustad notes, Williams would have disliked the term “toleration” because it suggests a concession, not a right). The idea that the state should not enforce or limit religious opinion was an eccentric view in the mid-seventeenth century that grew in popularity during the Enlightenment and became enshrined in the First Amendment. Yet Williams's perspective differed from Jefferson's and Madison's because it did not rest on indifference to others' religious views, but rather on a perfectionism so radical that no church ever attained his standard of purity, including the one he founded in Providence and left a few months later.

Gaustad makes a useful contribution to popular understanding by presenting Williams's Puritan ideas, with all their paradox and eccentricity, in their seventeenth-century context, before tracing his “legacy” of religious freedom in America. In celebrating his subject, Gaustad emphasizes some less-known aspects of Williams: his egalitarianism as a colonial leader, his links with Cromwell and Milton, and his anthropological writing about Native Americans. This biography is not wholly new, however. It is a reissue of Gaustad's Prophet of Liberty (2001) plus an additional chapter. Aimed at the general reader, these two biographies are based on Gaustad's more detailed work, Liberty of Conscience: Roger Williams in America (1991). Besides being more accessibly written, Gaustad's shorter versions are better structured for the reader seeking an intellectual profile of Williams rather than a blow-by-blow account. Although the chapters are roughly chronological, they overlap in order to encompass a theme, such as Williams's theory and practice of governance, his relations with Indians, and his philosophy of religious liberty. In the new chapter, Gaustad demonstrates how Williams's views fitted together, arguing that Williams's radical interpretation of the extent to which Christ's “new dispensation” superseded the Old Testament underlay his disagreements with other Puritans.