So I agree with the grandparent comment: unless one takes the time to study and truly understand other belief systems, it's hard to see how Western "secular" schools of thought remain Christian because we're submerged in them since childhood.
This is laughable... Someone needs to read more about classical antiquity! :) Certainly not something banal as "utopian political projects", which is extremely well attested in e.g. Greek philosophy, and indeed relatively absent from Christianity (its message being essentially escathological in nature, especially in its first few centuries)!
I don't think this is actually true; I think your own bias is colouring the conversation here.
The minimalist claim that the West is massively influenced by the Church is true to the point of banality, the maximalist claims those ideas are usually deployed to champion simply do not follow.
If only there were a name for this rhetorical fallacy...