Paradoxically, however, in defending the liberty of the Church and in refocusing their attention upon its spiritual role, Catholics also became liberals. Probably the best (and most intriguing) example of this is to be found in the writings of Felicité de Lamennais. The atheism of the modern state led him first to denounce the alliance of throne and altar and then to embrace the slogan of God and Liberty. Next came a messianic humanitarianism and what Perreau-Saussine describes as a church-free Christianity. A free church in a free state was to become the watchword of liberal Catholicism. 

It is clear that there was much about these ultramontane developments with which Perreau-Saussine feels uneasy. The ultramontane tendency, he writes, resulted in a disciplined Church but one that was "an empty shell, reactionary and sectarian". In particular, he regrets the abandonment of the search for a harmony between religious and political life. As he emphasises, infallibility had no implications for papal authority in matters of law and politics. From this follows Perreau-Saussine's admiration for Alexis de Tocqueville — the greatest political thinker of the 19th century, in his opinion — and an endorsement of Tocqueville's view that democracy can and should be both restrained and educated by Christianity. Later in the book he expresses his approval of the liberal Gallicanism of the contemporary writer Pierre Manent. He also sees the Second Vatican Council, with its recognition of the political role and primacy of the laity, as marking the reconciliation of the Catholic Church with this liberal Gallican tradition. The balance between the temporal and the spiritual was reaffirmed, with the result that the Church at last found itself at ease in the world of democracy. As Perreau-Saussine writes: "For all that religion can pose a danger to the state, this risk arises not only when religion is too political, as is generally imagined, but also when it is too apolitical, when believers develop a tendency to see nothing beyond their own religious group and become oblivious of the civic community to which they also belong." The believer, in other words, should also be a proud and active citizen.

This, of course, has never been an easy matter, especially in France. Robespierre was not the last voice of intolerant secularism. After the Cult of the Supreme Being came the ludicrous religion of theophilanthropy and a succession of attempts to establish a lay secular power that would act as a substitute for Catholicism. In the 19th century Auguste Comte founded the religion of humanity, with its own rituals and calendar; indeed, Comtean positivism became the quasi-official dogma of the French Third Republic after 1870. A republican catechism was now deployed through the state school system to educate children to become enlightened, autonomous and free citizens. "Laicism", the new state doctrine, quickly turned into anti-clericalism. The 1901 law on freedom of association was used to criminalise religious activities. The separation of Church and state that followed in 1905 was used to cow the Church into submission. Religious faith was reduced to a purely private matter, thereby denying the Catholic concept of the Church as a society and a communion. Perreau-Saussine cites Charles Péguy as one of the few French writers who showed how Catholics and laicist republicans might find common ground.