The French relationship to the Church has been odd for a while. Royal Gallicanism amounted to a de facto Protestantism (a la Anglicanism) while remaining inside the communion.

The term "eldest daughter" is interesting, as it perhaps goes back to the medieval split between France and Italy over the natural home of the Church.

The term "eldest daughter" is interesting, as it perhaps goes back to the medieval split between France and Italy over the natural home of the Church.

here:
The country of France was Christianized soon after the death of Christ. Tradition has it that St. Lazarus was Bishop there and even St. Mary Magdalene worked there spreading the Gospel of Christ. When St. Remigius baptized King Clovis virtually the whole country embraced the Catholic Church.

also, st. louis:
In all these deeds, Louis IX tried to fulfill the duty of France, which was seen as "the eldest daughter of the Church" (la fille aînée de l'Église), a tradition of protector of the Church going back to the Franks and Charlemagne, who had been crowned in Rome in 800. Indeed, the official Latin title of the kings of France was Rex Francorum,', i.e. "king of the Franks," and the kings of France were also known by the title "very Christian king" (Rex Christianissimus). The relationship between France and the papacy was at its peak in the 12th and 13th centuries, and most of the crusades were actually called by the popes from French soil. Eventually, in 1309, Pope Clement V even left Rome and relocated to the French city of Avignon.

As I remember, Charlemagne bailed out the Pope when he wasn't doing too well, and became Emperor as a reward. Log-rolling. Both the Pope and Charlemagne were under some pressure from the Eastern Church and the Eastern Empire, which were still very viable while the West was in decline. This was not theological -- the schism was sometime after 1000. But papal independence, give key support by Charlemagne, made the later schism possible.

Mon Dieux! This is not news mes enfants, literally, centuries. Spain was mostly Moslem for several centuries, please recall, and it made nary a dent in the Christian inclinations of the Iberian pensinsual, though it did leave some stunning architecture.
As early as the late 18th century it was generally noted that Frenchmen were not terribly observant. When Lewis Carroll traveled in France he remarked that it was mostly women and girls who engaged in Church devotions. In Flaubert's Sentimental Education (takes place during the 1840s), native French are not necessarily assumed to be "practicant" even though they were almost certainly baptized, and part of their cultural identity was Roman. Those who "practised" were noted as "Catholics."
Charlotte Bronte fell in love with a married professor in Brussels, Belgium while she studied there. Far greater than the gothic tale Jane Eyre, was her novel, Villette. Charlotte, good daughter of an Anglican clergyman that she was, had an aversion to Catholicism, considering it a prison of superstition. Yet she admired the professor's unabashed faith. To wit,
"Most of M. Emanuel's brother Professors were emancipated free-thinkers, infidels, atheists; and many of them men whose lives would not bear scrutiny; he was more like a knight of old, religious in his way, and of spotless fame. Innocent childhood, beautiful youth were safe at his side. He had vivid passions, keen feelings, but his pure honour and his artless piety were the strong charm that kept the lions couchant."

The point of citation is to show that the French speaking countries of Europe have been agnostic in practice for some time, though the culture could no more dispense with Catholicism than the Bayeaux tapestry could dispense with the Battle of Hastings.

garble correction:
This is not news mes enfants, literally, centuries. ... and it made nary a dent in the Christian inclinations of the Iberian pensinsual,

I mean "... for centuries what is now Spain was mostly Moslem (actually I don't know the stats but it was ruled by Moslems), and please, recall, Islam made nary a dent in the Christian inclinations of the Iberian peninsula..."

VA, the Muslims were driven out with the Jews.

During the Nineteenth Century conventional middle-class small-town Frenchmen were often aggressively secular, materialist, Darwinist, atheist, etc.

Free translation: "Belief in god remained stable at ~75% until the 60s....... but fell to 69 in 2000, 61 in 2005, and 51 today."

[So there was recent rapid change.]

Some of it came because some Christians (5%) refused to call themselves Catholics, Protestants, or Orthodox.

"Without religion" is 31%

Only 18% of the French are Catholics who believe in a personal God; apparently 33% remain Catholic without this belief.Only 20% of Catholics believe in priestly celibacy or an exclusively male priesthood. Strong Catholics amount to about 10% of the population.

Good grief, you mean that 33% of the French believe in an infallible Pope but not a personal God?

"VA, the Muslims were driven out with the Jews.

"During the Nineteenth Century conventional middle-class small-town Frenchmen were often aggressively secular, materialist, Darwinist, atheist, etc."

Oui, voila. and your point is...?
the more things change the more they remain the same?
Speaking of Jews, many of those of Provence converted to Christianity under duress, and added a mysterious quality to the religious mix. Southern France had always been fertile ground for outliers and "heretics." Terrible things happened there in the form of persecution. As we all know, Nostradamus, whose very name is an infusion of Gallic Catholicism, was of converted Jewish background, but he did ok for himself, all things considered.
In any case, current organized religions best known in the world today, have pretty much flickered out as blueprints for culture or civilization. No more sacred geometry of the gothic cathedrals, or Bach B minor masses, composed in such sublime mathematical precision, will rise from their embers. Sorry for the euro-centricity, but it's what I know best.
The constructive fire is out and all that is left is noxious smoke.
What happens next is up in the air. I wouldn't count on science or some idealogy organizing "spirituality." Half the world has been been there, done that and it didn't work.