Religious observance plays an important part in the lives of many French people, but its importance in national life has diminished through the years, as it has in most European countries. France has traditionally been a strongly Roman Catholic nation. The powers of church and state were closely related under the monarchy, with powerful cardinals, such as Richelieu and Mazarin, serving as the king's principal ministers (see Richelieu). Except for a period of tolerance under the Edict of Nantes, which was issued in 1598 and revoked in 1685, France was bitterly hostile to the Protestant movement. Many of the bloodiest periods of French history involved the wars of religion that ravaged Europe for over a century.

During the French Revolution, from 1789 to 1799, measures were taken to reduce the power of the church and to separate religious and civil authority. Religious freedom was granted in 1795. Catholicism remains the major religion in France, but most Protestant sects are active in the country. They are especially strong in Alsace, the northern Jura, the southern Massif Central, and the central Atlantic region. The historic depth of religious feeling in France is perhaps best reflected by the nation's magnificent cathedrals.

The Jewish community in France, though relatively small, has had a strong influence on the economic and cultural life of the nation. More recently, the arrival of many workers and their families from former French colonies in North Africa has created substantial Muslim populations and an expansion of the religion of Islam. Most French Jews and Muslims live in Paris, Lyon, and Marseilles.