You are wrong there. Humanist ideas were challenging the Christian orthodoxy from the Renaissance. The Enlightenment has been advancing ever since, with orthodox Christians resisting every new idea and challenging every scientific and rational dialogue since Galileo.
I was thinking more along moral and social norms lines. Certainly the Churchs absolute power was challenged as being authorative in all domains of life including how we should gain knowledege but I think it still had hold over society when it came to morals even when the Church was subject to the Monarchy and later the State to some extent.
We only have to look at some of the social norms and moral laws over history to find a consistent influence. For example in the 14th century, premarital sex was prohibited and considered a sin and this was still the case pre 1960 in most Western nations regardless of Enligtened thinking. This was similar for a number of moral issues like adultery, homosexuality, SSM aned abortion.
The Church had absolute rule up to around the 1500's but still shared rule with the Monarchs up until Enlightenment. Enligtenment had a profound effect on how people thought about everything but still Christain values had sway on laws and especially social norms. The Romantic period that followed Enlightenment reignited the Church or at least belief in God and a more pure religion.
I think Enlightenment began the process of rationalizing morality which had its own problems but I don;t think the pioneers were wanting to get ride of God as the basis for society. We see that in the US Declaration that all are created in Gods image with natural inalienable rights. But certainly Enlightenment led to branches that contested God as the basis of morality altogether.
I think we have seen the culmination of this progressive thinking during the 20th century and especially from the 60's as these ideas like liberation, Humanism, Individualism and Materialism worked together to result in cultural revolutions.
Then came Postmodernism ( the idea that there are no Grand truths and truth is self referential) and then the academics with Critical theory designed to tear down the status quo due to oppressor/oppressee relationships Which has evolved into Wokism the idea that Identity is the only truth and denying identity is denying Human Rights.
I know its more complex than this but broadly I think from the time of Christ which was a significant event in Western and human history has impacted humans and has taken a long time to shake off, not that it will ever be completely shaken off. But we are entering what some say is the Anthropocene (the time of Humans). So maybe now humans are replacing God with themselves, to recreate the Utopia that everyone has been yearning for which includes human ideas on morality and how we should order society.
It may be that by the second half of the Twentieth Century something of a tipping point occurred as numbers of people in many countries, including my own, distanced themselves from religious institutions. It seems that many Christians seem to regard themselves as outnumbered these days.
Yes I think that seems to be the case that Christainity dwindling. As well as whats mentioned above this was compounded by the Church behaving badly.
But primarily I don't think that would stop people from believing if they are rational and honest because bad behaviour in some parts of the Church doesn't represent Christain belief (Christs teachings). I think its more about belief, we all have this belief shape hole in us and you can make anything a god. The question is what do we fill the void when we take God (Christainity) out of the picture.