John Locke is acknowledged to be one of the theoretical founders of the separation of church and state, a distinguishing feature of modern liberal democracies. Though Locke’s arguments for the merits of such separation have been subject to extensive investigation, his argument for its feasibility has remained relatively unexamined. This article argues that Locke was confident that separation of church and state can successfully be implemented in all times and places because of his epistemological and psychological insights that human beings (...) are moved to act by unease and that separating church and state removes the unease that causes religiously based political instability. We conclude by noting that Locke’s understanding of unease is foundational for his larger ambition to secure political liberty. (shrink)