Well I am talking in particular about history–presuppositions about history. If we were to choose to start counting the years somewhere (i.e. a year 0 CE), we could throw the dice or we could try to come up with some kind of rubric for choosing a date. Now, no one did either of those and the date was determined early on and I imagine that Wikipedia article probably gave a good summary of how it happened though I didn’t actually read it. Regardless, historians can probably give some insightful comments about geopolitical movements, cultural imperialism, etc.
I am simply saying that, hmmm, is it just a coincidence that the worldview which set 0 CE (Christianity) also happens to be the one and only worldview that does not ask for any presuppositions about history? I don’t think so. I think that Christianity set the year 0 because it was the one and only worldview that did not ask for any blind-faith beliefs about God, about history, or about the world. All the other word views say that before you look at history you need to first arbitrarily choose to believe certain things to be true.
Apart from historical matters–such as the issues you mentioned about whether objective truth exists, whether God exists, whether morality exists–99.9% of the planet has treated those as self-evident truths throughout history. It is only with outrageous rhetorical gymnastics, extremely stubborn obfuscation, and political disconnection from reality (the kind of disconnection that leads to justifying things like the Holocaust or the Killing Fields or the mass re-education camps in China, etc.) before those become issues and before we “debate” moral issues like whether pornography is oppressive or whether suicide is healthy, etc.
I try to avoid all that as much as possible. Somewhere out there the fields are white for harvest for those who are hungry to know who God is and what he has done. So I’m just talking about presuppositions about history.