Tensions between Protestantism and Catholicism dominated politics in nineteenth-century Canada, occasionally erupting into violence. While some liberal politicians and community leaders believed that equal treatment of Protestants and Catholics would defuse these ancient quarrels, other Protestant liberals perceived a battle for the soul of the nation.

Protestant Liberty offers a new interpretation of nineteenth-century liberalism by re-examining the role of religion in Canadian politics. While this era's liberal thought is often characterized as being neutral toward religion, James Forbes argues that the origins of Canadian liberalism were firmly rooted in the British tradition of Protestantism and were based on the premise of guarding against the advance of supposedly illiberal faiths, especially Catholicism. After the union of Upper Canada with predominantly French-Catholic Lower Canada in 1840, this Protestant ideal of liberty came into conflict with a more neutral alternative that sought to strip liberalism of its religious associations in order to appeal to Catholic voters and allies. In a decisive break from their Protestant heritage, these liberals redefined their ideology in secular-materialist terms by emphasizing free trade and private property over faith and culture.

In tracing how the Confederation generation competed to establish a unifying vision for the nation, Protestant Liberty reveals religion and religious differences at the centre of this story.