D. G. Hart chronicles the transatlantic history of Presbyterianism as a political movement from the sixteenth to the nineteenth centuries, tracing its evolution into a modern, liberal religion. Historians have often described Presbyterianism as a political orientation that leads to rebellion and revolution. D. G. Hart interrogates this assumption, presenting instead a complex narrative of Presbyterian understanding of political authority and the role of the church in society. Synthesizing Presbyterian developments in England, Scotland, Ireland, the United States, and Canada from 1560 to 1870, Hart compellingly explains first why Presbyterianism was politically disruptive in Britain for 150 years and then how these Protestants adjusted to liberal democracy. The truly revolutionary side of Presbyterianism took place during the religious and parliamentary wars of Scotland and England during the 1630s and 1640s—almost 150 years before the American Revolution. After 1640, Presbyterians remained politically assertive, but switched from state churches and covenanted monarchs to civil and religious liberties and republican government. Even so, fallout from the age of revolution extended to Presbyterian involvement in the American Founding and the formation of the Dominion of Canada. Ultimately, as a rigorous faith that refused political compromise, Presbyterianism unintentionally laid the groundwork for religious disestablishment and religious freedom. In so doing, Presbyterians became unlikely defenders of liberal democracy.