The events you mention still took place within the Abrahamic framework of thought. Ideas like a linear timeline progressing from A to B (rather than a cyclical one) or utopian political projects bringing final justice to society are Abrahamic in nature.

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.