Long story short, the west got heavily secularized. First it was minor things most people would agree with like separation between church and state, then all the modern "scientific" theories came around, "enlightenment", etc. Then the communists noticed Christendom was the main stumbling block in the way of them taking places like the US, inverted the original Marxist theory (Marx thought things like family and religion were a superstructure built on the foundation of capitalism, they realized it was the opposite) and started heavily undermining the west to the point it became the most secularized civilization to ever have existed.
Now consider the Islamic world: none of the things mentioned above ever happened there. Some Muslim guy from Yemen still thinks the world is flat, still marries his daughters off at 12, still forces women to behave decently and respect men. It's not because "Islam is based and Christianity is cucked!!11", - the bible is also all for young marriages, women obeying men, also has a cosmological model which gives way more support to the flat model and all that, it's just that the modern version of Christianity we know is as hollow an air balloon. It's basically a re-reading of the bible through the modern secularized lenses.