Eighteenth- and nineteenth-century France incubated a remarkably coherent esoteric Christianity. Neoplatonism, Hermeticism, Rosicrucianism, Freemasonry, Christian Kabbalah, and a revived Gnostic liturgy converged around the doctrine of réintégration—the return of all beings to Divine Unity in the Logos. Moving from Martinès de Pasqually’s theurgy and Saint-Martin’s interior path to Lévi’s symbolic synthesis, Papus’s initiatory codification, and Doinel’s Eucharistic vision, this book shows how a “Christian non-duality” took public form in lodges, journals, and churches. Far from a syncretic curiosity, the French tradition offers a rigorous, historically grounded account of unity that speaks fluently with Buddhism, Vedānta, and Taoism while remaining unmistakably Christian.