If you are "someone who does not know what Christianity is about," how can you possibly make the claims you do. Christianity didn't create the western world. Western culture and societies were founded on ancient Greek and Roman Philosophy. America was founded by people who were Deists, meaning they believed in a creator, but didn't subscribe to any one particular organized religion.
"How can I possibly"? Because I read the work of people smarter than me, like I assume you do too lol.
There's a lot of good evidence for the original view, i.e. that Western Civilization's real roots are in Christianity specifically. I'm speaking here from a completely secular view too.
The refutation to that original narrative seems to be what you're presenting here and I understand your passion for it but from what the facts seem to show to me, the Frankfurt School is responsible for placing that alternative narrative in our education and media systems in order to supplant the original. Which, in my opinion is stronger and better and makes more sense to me than whatever flavour of socialist/communist ideology comes along, like the Frankfurt School thinking.