I'm still trying to figure out how you come to the conclusion that acting in direct contradiction to all that Christianity stands for is the 'natural aftermath' of Christianity.
Explicitly contradictory to its moral foundations, but then taking
parts of its ethics far away from sense. Christianity specifically denying kings any special exception from morality is a divergence from the preceding commonality of god-kings and religious justifications that enormous exploitation of subordinates is fine, being a
very clear part of the philosophical lineage responsible for the modern concept of equality of people that is at the core of Communism's fuckups.
Complaining that it's too good at it's job of holding your civilization together that it makes counter movements especially brutal is certainly an odd take though.
I suppose it's better phrased as a massive problem with "brittle" ethics, in that by tying almost all of moral behavior to a small set of premises and working to remove external ones the counter-movements that
do take off are much more severe, abrupt, and hard to correct than under most other moral frameworks.
We are not in a position to compare post-Christian Europe with "never-was-Christian" Europe, as the latter is purely a what-if.
We can, however, compare the before-and-after: Imperial Roman polytheism worked to keep people on the same page for "big picture" matters to hold the Empire together but was largely unconcerned with theological minutia of how who related to who or the exact setup of rituals, whereas Christianity worked to have only "One True Way" for viewing the world as a whole and saw remarkably routine
street riots over such fine details the "mainstream" was unconcerned with enforcing.
So now... are you saying this is a good or bad thing? Would you prefer a system like that of China?
Good thing, hence the next sentence starting with "though" to denote a separate matter that's a bad thing.