The Swiss-born philosopher and politician Benjamin Constant (1767-1830), one of the founders of 19th-century liberalism, sought in his five-volume treatise On Religion to provide a comprehensive history of religion in its various forms and manifestations. Despite his commitment to the separation of church and state and to religious toleration, Constant argued that religion—any religion—is necessary to the flourishing of society. On the occasion of the publication of the first complete English translation of On Religion, Gianna Englert writes:

“By studying the epochs when the religious sentiment triumphed,” [Constant] concluded, “one sees that in every one liberty was its companion.” For Constant, the choice was between religious sentiment and self-interest, or to put it more strongly, between self-sacrifice and egoistic materialism. Absent the direction of religion, he worried that human beings would accept self-interest as the foundation of both individual morality and public life. In so doing, they would lose the beauty and nobility of religion, that which is definitively and uniquely human—and their political freedom as well.

Constant regarded self-interest as a thin, unstable foundation for societies that would lead eventually to isolation and “the hunger for wealth,” . . . arguing that the private life governed by self-interest is less than human, fit only for “industrious beavers . . . or the well-regimented activities of bees,” not for human communities. He worried that a society so constituted was susceptible to tyranny, since it was simply a collection of isolated persons who cared little about protecting free institutions.

What exactly does religion do to counteract these tendencies? Constant offers many answers throughout the book. Religion tells us “what is evil and what is good,” “reveals to us an infinite being,” and creates “order.” . . . On an individual level, religion sets our sights above material wellbeing to encourage the capacity for self-development. It gives us spiritual goals that extend beyond our immediate wants and needs. Most importantly, it encourages us to sacrifice for those goals, promoting a “certain abnegation of ourselves.” This, in turn, serves political institutions that can become “empty forms when no one will sacrifice for them.”