Book excerpt: This book seeks to bring coherence to two of the most studied periods in British history, Caroline non-conformity (pre-1640) and the British revolution (post-1642). It does so by focusing on the pivotal years of 1638–44 where debates around non-conformity within the Church of England morphed into a revolution between Parliament and its king. Parliament, saddled with the responsibility of re-defining England’s church, called its Westminster assembly of divines to debate and define the content and boundaries of that new church. Typically this period has been studied as either an ecclesiastical power struggle between Presbyterians and independents, or as the harbinger of modern religious toleration. This book challenges those assumptions and provides an entirely new framework for understanding one of the most important moments in British history.