This article compares different historical accounts of early Christianity written by François Guizot, Benjamin Constant and Madame de Staël and shows that they played a significant role in the construction of their ideas about religious tolerance and political liberty in ancient and modern states. In his 1812 translation of Gibbon’s $Decline\; and\; Fall\; of\; the\; Roman\; Empire$ Guizot used his editorial footnotes to oppose Gibbon’s sceptical representation of the early Church and to assert that the development of Christianity had been crucial in condemning slavery, establishing religious toleration and fostering individual liberty. Benjamin Constant also opposed Gibbon’s representation of early Church history but he argued in his posthumously published $Du\; polythéisme\; romain$ (1833) that the key achievement of the early Christians had been to revive the idea of individual religious sentiment against the anti-individualist Roman state. As Guizot developed his historical research in the 1820s he rejected this view and came to see the early Christians as demonstrating the inherently social nature of all religious practice. Some of these ideas were anticipated by Madame de Staël in $De\; la\; littérature$ (1800), but all three thinkers sought to reintegrate religion into their ideas of modern liberty in ways that merit greater attention.