The Huguenot scholar Jean Henri Samuel Formey (1711–1797) is nowadays best known for his role as the secretary of the Berlin Academy of Science, his large learned correspondence and his Christian refutations of Rousseau and Diderot. Less known is his collaboration to the famous Parisian Encyclopédie which in the scholarship is usually considered as the symbol of the Enlightenment’s pursuit of reason and criticism of dogma. Almost forgotten is that at the origin of Formey’s collaboration to the Encyclopédie was his own encyclopedia project on which he worked for several years at about the same when the idea of the Parisian encyclopedic endeavor was born: since January 1742 he compiled material for a philosophical encyclopedia which he eventually sold to the Encyclopédie’s publishers in 1747. The publication history of Formey’s unfinished encyclopedia is hence an important source for contextualising and understanding the articles of the Encyclopédie that relied on his work. More importantly, however, it can help to diversify our concept of the eighteenth century’s most famous encyclopedia, particularly in regard to religion. My aim with this paper is to depict the multiple motivations that informed Formey’s encyclopedic practice and to discuss how his self-concept as a Christian philosopher conditioned the content and form of his encyclopedia articles. To this end I will offer an interpretation of his article DIEU as it appeared in the Encyclopédie based on Formey’s concepts of philosophy and of the encyclopedia as a philosophical genre.