The Cult of the Supreme Being (French: Culte de l'Être suprême) was a religion based on deism devised by Maximilien Robespierre, intended to become the state religion after the French Revolution.
Robespierre strictly believed that there was someone who was watching over France, and that was the Supreme Being. The cult represents an innovation in the "de-Christianization" of French society during the Revolution, in that Robespierre sought to move beyond simple agnosticism (often described as Voltairean by its adherents) to a new and, in his view, more rational devotion to the Godhead. (Compare the cult of Reason, advocated by the Jacques Hébert and the enragés, and explicitly opposed to Robespierre's more theistic conception of the Supreme Being.)
It was Robespierre's proclamation of the cult as the new state religion in 1794 that prompted the coup d'état of 9 Thermidor and set in train the subsequent political reaction. The Cult of the Supreme Being was thus aborted almost instantly.