The French Revolution was a fundamental break with the old order. And that also included religion. The people desecrated the churches, and many priests fled the country. Atheism seemed to triumph. But Robespierre opposed this anti-religious movement. The Virtuous One created a new state religion - with the Supreme Being as its new deity. The Convention decreed the immortality of the soul. The Festival of the Supreme Being on the Champ de Mars on 8 June 1794 was the high point of the new cult. It took place in splendid weather. The people were cheerful and full of hope. Two days later, the Great Terror began.
1789 - 1801
November 2, 1789 · The National Assembly decides to nationalize Church property. The Church is thereby effectively expropriated.
November 27, 1790 · Priests are required to swear an oath to the Civil Constitution of the Clergy. Many clergymen refuse the oath. In doing so, they make themselves enemies of the Revolution.
September 1792 · During the September Massacres, priests who refused the oath are also killed.
November 10, 1793 · Festival of Reason in the former church of Notre-Dame in Paris. Robespierre rejects this atheist movement. He plans to introduce a new state religion.
May 7, 1794 · The National Convention recognizes the existence of the Supreme Being and the immortality of the soul.
June 8, 1794 · Festival of the Supreme Being on the Champ de Mars in Paris (20 Prairial Year II). The high point of the new state religion.
July 28, 1794 · Execution of Robespierre. The Cult of the Supreme Being thereby loses its main support.
August 22, 1795 · The Constitution of Year III is proclaimed in the name of the Supreme Being (Art. 1).
1797 · Director La Révellière-Lépeaux attempts to introduce a substitute religion for Catholicism: Theophilanthropy, a deistic moral doctrine. The Directory supports ceremonies in Paris churches. These, however, attract only modest attendance.
October 4, 1801 · The Consulate bans Theophilanthropic meetings in public buildings.
Quotes
The French people acknowledge the existence of the Supreme Being and the immortality of the soul. Article 1 of the decree of 18 Floréal Year II (7 May 1794).
Yes, Robespierre, there truly is a Supreme Being. Remark attributed to a sans-culotte when Robespierre, seriously wounded, was at the Committee of Public Safety during the night of 9–10 Thermidor Year II (27/28 July 1794).
To found his religion, Jesus Christ was crucified and resurrected. You should have tried to do as much. Talleyrand to La Révellière-Lépeaux, May 1797.