I think you may be interested in this.
https://mereorthodoxy.com/categorizing-benedict-option-communities-christianity/
The article divides the involvement of Christianity with the world into three options. I list them in order of decreasing involvement:
– The «Illiberal Catholics» are, among others, the Middle Age Catholics, when the State was a Catholic state. The entire society was organized according to a confessional Catholic state. The Orthodox have traditionally adopted this model too. (I think the Muslim equivalent would be the theocratic Muslim state, but I am not an expert).
– The «Magisterial Protestants» separate Church and State by privatizing religiosity. The ordinary life is religious life because each individual is a priest and his vocation is his sacred duty. Secular activities are only a different way of worshipping God. («Opus Dei», a Catholic movement, follows this philosophy, no doubt borrowed from the Protestants)
– The «Augustinian radicals» would be the current Catholics (and other denominations too), that consider the Church and the World as completely separated. Religious activities and secular activities are different. This produces the difference of religiosity between the clergy and the lay people that you describe in your post.
I think early Christians were «Augustinian radicals». Since Rome was a pagan State with a hostile official religion, Christians had to separate themselves from the world. From Constantine on, the option preferred were «illiberal Catholic», that is a confessional State, (which is also the option preferred by the Orthodox Christianity, with its national churches)
Luther introduced the principle «each believer can interpret the Bible as the Holy Spirit allows him to». This could only end up with Protestantism divided in hundreds of sects. This division ended up producing separation of Church and State, because the state could not have one official sect when its citizens belonged to tens of sects. (I am simplifying this, but I don’t want to bore you with details). This separation began in Protestant states and then it was transmitted to Catholic states.
This separation of Church and State prevented any version of Christianity from being the official religion. Since each State needs an official religion (which is the basis of the Law), the Enlightenment philosophy (liberty, equality, democracy) ended up being the official religion.
With a hostile official religion, Christians had to privatize their beliefs. Protestants did it with the model of «magisterial Protestants» while Catholics went back to the model of «Augustinian radicals».