Robert Louis Wilken, the William R. Kenan Professor Emeritus of the History of Christianity at the University of Virginia, has written an intellectual history of the ideas surrounding freedom of religion. Liberty in the Things of God: The Christian Origins of Religious Freedom (Yale University Press, 2019) offers a revisionist history of how the ideas of freedom of conscience and freedom of religion originated in the writings of the Christian fathers of the early Church, such as Tertullian and Lactantius, during the period when Christians were a persecuted sect of the Roman Empire. Wilken argues that it was not the political theorists of the Enlightenment who invented religious freedom in response to the wars of the Reformation, but rather the participants of the Reformation itself, including both Protestant and Catholic thinkers, who recovered ideas from the Roman-era Church fathers and used them to develop arguments about religious liberty for both individuals and faith communities. Wilken demonstrates that the concerns about whether faith could ever be enforced by the sword were present from the beginnings of Christianity. Wilken’s book helps inform our understanding of the origins of religious liberty, which is a concept of great import in contemporary debates about the meaning of the First Amendment’s Free Exercise and Establishment Clauses.