As a former resident of Quebec (1970s), and in partial (and belated) response to a post by my good friend Bill (see here), I'd say I witnessed the effects of the Revolution Tranquille in declericalizing and secularizing the province. I can't quite see a parallel in the United States for two reasons:
(a) Quebec, like Ireland and Poland, was fiercely Catholic as a matter of national identity because it faced a Protestant conqueror (in the case of Poland, one that was Orthodox, later Communist, but in an Orthodox way). Remove the British and the Russians and religious fervor waned. Poland legalized abortion just a few years after the Soviet Union collapsed.
(b) The USA is a predominantly Protestant society, with a Protestant epistemology. Protestantism itself was the major secularizing force in northwestern Europe, transforming religion from an artifact controlled by a clerical caste based in Rome to an assertion of the freedom to engage in individualistic profession of an endless variety of idea systems.
The origin of secularism in Christian Europe across confessional lines lies, paradoxically, in Christianity. The Christian acceptance of nominalism in its ranks between the third and sixth centuries of our era, when missionaries started converting entire Barbarian tribes by convincing their king or chieftain sowed the seeds of secularism.
Christendom (RIP...DG!) was an edifice built on compulsory religious affiliation that never developed authentic deep roots of faith among the mass of Europeans. They were what we would call cultural Christians and nothing more. The continued existence of pagan shrines throughout supposedly Christianized Europe as late as the 12th and 13th centuries gives witness to this.
Enter industrialization and capitalism, both arguably the children of Protestantism (see Weber), and the Church and churches lost the working class. That happened in the 19th century.
What we have witnessed in our lifetime is a belated echo in America, where religion was socially compulsory, a matter of manners more than conviction. Among urban, educated Americans the compulsion has slackened to the point that religious ignorance is the prevailing coin of the realm. Maybe that's more honest.