We will never know where would have been if it wasn’t for the iron grip of the Christian church on western civilization for 1200+ years, but the secularization of society in the last 200 does indicate that we made rapid progress in medicine, human rights and science/technology when no longer were bound by the control structures of the church.
Why might Western Europe have advanced faster than other cultures that weren't "under the iron grip of the Christian church"?
Islamic civilization, in particular, made crucial contributions during that time. Newton couldn't have invented modern physics without hundreds of years of preparation by Islamic mathematicians (including Arabic numerals, algebra, and trigonometry).
And it was really Rome, not Christianity, that was responsible for the stagnation in the west. The Romans were great at practical application but contributed very little new theoretical knowledge even before they converted to Christianity.
What progress was made during the six hundred years between Aristotle and Constantine?
To add to that, a lot of this modern progress was timed with the rise of protestsnism and a certain country specifically found as a refuge for persecuted protestants (not atheists). But that is just one factor, you also have trans-atlantic slave trading and the raping of africa and the colonization of india, all of this allowed many in the west less time in the farms and stables and more time at universities and studying.
Isaac newton was forced to go back home and labor in the farm for a while until people convinced his mom to send him back to uni for example.
How much of the latter is correlation without causation? Would edison and tesla have been prevented by the catholic church from working on electricity? Or Ford on cars? I mean in their time still, you didn't have a theocratic state but society was much more religious. In the 1800s, congress used to have church service at capitol hill and all members would attend for example.
