I'm taking my chances on mind-killing here, but I'm (ethnically) Jewish, and my reflexive take on Christianity is "unreliable" rather than "holds civilization together".

In the interests of avoiding the obvious... WWI was committed by Christian nations.

I believe (without having done a bunch of research) that a lot of the "tear it down" in current culture comes ultimately from seeing the hope of civilization's steady improvement was inaccurate after the governments of Europe couldn't find a way to avoid killing millions of each other's citizens.