Contemporary American political thought has not strayed from the old Catholic world. This is one of several important insights offered by historian Michael Breidenbach in this well-written and ambitious book. He argues that Republicanism and Atlantic Revolutionary ideologies have been underwritten by Catholic notions of conciliarism and a tradition of anti-papalism. In brief, these two concepts hold that the Pope has no right to intervene in the civil affairs of any political entity. Moreover, conciliarism and anti-papalism advocated for a mixed constitutionalism. A ruler ought to be constrained by the rules of a constitutional game. The Pope himself, Catholic conciliarists and anti-papalists held, was subject to the collective powers of the bishops, and even more importantly, the Catholic faithful. These Catholics did not trust a leader that operated outside of a constitution. The Pope possessed a spiritual power but did not rightly wield sovereignty over a civil kingdom; conciliarists and anti-papalists delineate the realms of church and state.

What Breidenbach suggests is that Protestants and Enlightenment thinkers never actually succeeded in “de-Catholicizing” American political revolutionary thought, and maybe even modern thought more broadly. Separation of church and state, and religious liberty, carry Catholic genealogies. We might read Our Dear-Bought Liberty as demonstrating how the “right type” of Catholics (anti-papal, proto-democratic, humanist) won a significant political struggle in colonial and revolutionary America. Their victory ensured that Catholic arguments for limited authority and religious freedom influenced the American Revolution and the Constitution. Certainly, we must still account for why American and modern Catholic history remains full of integralists, centralists, authoritarians, papalists, and ultramontanes. But this book is an excellent point of departure for thinking about the Catholic influence on modern political thought.

Catholics felt compelled to incubate and purse conciliarist and anti-papalist modes of thought in response to the Papacy's early modern claim that a non-Catholic ruler could be deposed, even murdered. It was a difficult reputation to shake. This notion generated fears and anxieties among Protestants that were nearly impossible for Catholics to assuage. The tyrannicide clause, so mischievous, was a heavy version of the notion that Catholics could not be good subjects because of their persistent loyalty to the pope, a foreign power. John Locke essentially argued that conciliarist and anti-papalist Catholics were fakers. All Catholics, thought Locke, followed Robert Bellarmine's papal absolutism. Locke believed that Catholicism ought to be treated categorically as a threat to Protestant liberty and constitutionalism.

Breidenbach supports his book's propositions by following the political and intellectual careers of powerful Catholic gentry across a few generations. This focus on elites is not without limits, of course, but Breidenbach does well in speaking to wider social trends. The first part of Our Dear-Bought Liberty focuses on Cecil and George Calvert, the founders of Maryland; the second half of the book looks at the lives of the Carrols, particularly Charles and John. Breidenbach reconstructs Cecil's delicate quest to foster Christian toleration in Maryland, and he deftly reads the efforts of Cecil to rewrite oaths as evidence of Catholic republicanism. Cecil took the oath to the king while maintaining that such an action was genuinely Catholic on the grounds that he could support any civil leader completely: the pope, he held, had no jurisdiction in the secular sphere. Maryland denied a church establishment, codified religious toleration, and rejected sectarian oaths. Charles Carroll, the wealthiest man in seventeenth-century Maryland, an owner of over 500 slaves, continued along these lines: he denied the Pope's deposing power, he rejected the Pope's claims to jurisdiction over British soils, and he swore allegiance to the King.

Chapter 5, “No Papists,” is the high point of the book and a wonderful intellectual history of early modern Catholic Republican Thought that is Atlantic in scope. The reader is treated to a wide range of Catholic Whiggism and Republicanism that substantiates the author's main claims. Breidenbach shows how the Carrols, for example, were exposed to Jansenist arguments that councils were superior to the pope. He unpacks the arguments found in English priest Joseph Berrington's 1781 book, The State and Behavior of English Catholicism, which rejected the Pope's claim to monarchical powers. The chapter is full of dazzling turns of phrase like the following: “The ‘Machiavellian moment’ in America was as much about ecclesiastical republicanism as it was about political republicanism.” Medieval and Renaissance debates over papal authority echoed in the nation's founding documents.

The book concludes by showing how the American Catholic Church supported a republican political culture in the nascent United States of America. Breidenbach makes the case that the Catholic tradition of anti-papalism informed the American Revolution. He suggests it propped up the separation of church and state: “No church could dictate to a state, just as no state could dictate to a church.” The primary theorist of this idea was fourteenth-century writer John of Paris, not James Madison. When, in the 1950s and 1960s, John Courtney Murray went to craft his own arguments for a cleft between religious and secular orders—an intellectual edifice for religious liberty—he too turned to John of Paris. He rejected Bellarmine. Perhaps we historians should rethink John Locke: why would it matter if Locke did not think these Republican Catholics were real Catholics? We tend to assume that Locke's thoughts matter a great deal.

While this book does not necessarily help us explain why Catholics are still attracted to church-state mergers and various iterations political authoritarianism, it goes far in showing us the influence of Catholicism on modern constitutionalism. The arguments remain subtle and persuasive. This is an excellent book that deserves a wide readership.