The French and American revolutions were followed by a period of counter-revolution, during which also the conservative and dogmatic Western European Protestant and Reformed state churches tried to restrict the freedom of speech in the areas that were under their control.
On the other hand the economic development had by then already gained all new kind of momentum from the intellectual opening up of that happened in the 17th and 18th centuries. Economic progress did slowly create a new kind of wealthy middle class that had the interest and but most importantly the means to educate themselves and their children.

The Age of Enlightenment brought to the forefront the ancient Greek ideas of democracy and the freedom of the individual. The books containing these revolutionary ideas were now translated and published widely in the Western Europe.
These ideas got a warm reception from the emerging new middle class, who were searching for a way for making themselves heard in the feudally ruled world.
The ensuing emergence of modern science pushed the economic development to new heights in the Western Europe. The increasingly wealthy and more and more educated middle class was soon growing steadily.

This development was intensified in the northern parts of Europe by the fact that in the end also many of the leaders of the Protestant state churches were soon convinced of the growing importance of science.
Accordingly they did not mostly even try interfere with its rise, even if the Catholic Church still tried to do it in the countries that were still under its sway.
The practical implications of science and the economic growth that followed from its use to solve more and more practical and technical problems did eventually spread even to the Catholic world. Also there the intellectual supremacy of the Church was eroded little by little by the slow but inevitable strengthening of the secular parts of the society.

So, the secular power of the Christian churches was diminishing on all fronts of life. It was the more so, as the new findings of science did show clearly the true allegorical and fantastic nature of a increasing number of Biblical “truths”. Uncomfortable co-existence was, however, possible as long as science did not confront religion straight on.

Charles Darwin - Wikipedia

It was Charles Darwin who finally really challenged the Christian religion and its central teachings head-on with his revolutionary idea of evolution. Evolution is simply in no way compatible with the teachings of the Christian faith and the story of Creation presented in the Bible. This was finally a situation that could not be bypassed easily.
However, the world had by this stage been changed up to a point where it was impossible to put the genie back to the bottle.
Members of the society could with their own eyes easily see the concrete benefits that the advent of science was giving them. The Church simply could not challenge science anymore in western Europe with any kind hope of lasting success, at least.

The western Christian churches did of course condemn Darwin and his dangerous ideas with strong words and there is still a widespread resistance among truly believing Christian against his findings for a very good reason.
Charles Darwin did solve one of the greatest unsolved scientific mystery there was left at that time; where did humanity come from.
Not having a clear answer to this difficult and important question did for example lead to a situation where many of the founding fathers of the United Stated were deists or believers in divine explanation of the existence of universe, but where there is no personal god that has any interest in matters of human beings.
After Darwin up to that point common deism did disappear and was largely replaced by free-thinking and later atheism and agnosticism. Science now could finally provide most of the really important answers which had up to this time been explained with religious myths.

After Darwin the western Christian Protestant churches started their involuntary trek to their modern form, where they, in fact, do not try to impose their religious ideas to the whole of society anymore.
These religious organizations do not claim to be originators and carriers of all human wisdom anymore. They are mere givers of comfort and givers of a haven to those people who do not dare to face the real world as it is, which can of course be only a good thing.

(This little essay was refurbished on 22th of April, 2012)