Cult of the Supreme Being

The Cult of the Supreme Being was a cult in Paris, France during the time of the revolution, of which Maximilien de Robespierre was a prominent member. The cult's ideals of nationalism closely resemble those of the Templar Order.

The Festival
On 8 June, 1794, a festival was held honoring the Supreme Being. Robespierre was present, and the Assassin Arno Dorian found a few incriminating documents to discredit him.

Reference

 * Assassin's Creed: Unity