Not a single ancient civilization sealed itself off. From Catalhoyuk, through Sumer, Babylon, Indus Valley, and even Mesoamerican ones, to Egypt, Ancient Greece or Roman empire. Heck, even the separatist Chinese had a lively business with the rest of the world. Sure, the latter one was significantly less cosmopolitan that the former ones.

As for the rest -- the secular progress you talk about is the departure from institutionalized religion (not sure how it applies to NK, though, as that one is definitely not a theocracy in the traditional sense). As I said, you conflate institutionalized religion (well, there's no other kind of religion as far as I'm concerned), with a way of life. Only the former, which emerged only after civilizations were born, can be linked to theism or mysticism, while the latter is linked with utmost practicality (which inevitably includes skepticism and yes in some cases even straight out atheism--again, look up Pirahã people).

All in all, as I see it, you observe and judge relatively recent politics and try to extrapolate overarching and timeless philosophical conclusions from your observations. Not surprisingly, it does not work.