John Owen (1616-83) was the most significant theologian in 17th century England, and a key player in the revolution that created the English republic (1649-60). Rising from humble origins, he became preacher at the regicide of Charles I, chaplain to Oliver Cromwell in the invasions of Ireland and Scotland, vice chancellor of the University of Oxford, and the premier religious statesman of the Interregnum. The restoration of the monarchy pushed Owen into dissent, criminalizing his religious practice and driving his writing of eight million words in defense of high Calvinism and religious toleration. But Owen transcended his many experiences of defeat, and his claims to quietism were frequently undermined by rumors of his involvement in anti-government conspiracies. This religious biography traces the evolution of Owen's thinking and religious practice until his emergence as a leader of Restoration nonconformists.