How has deconstructionism and nihilism really been all that paradigm shifting?

If you really want to deconstruct the bible and monotheism in general, why not point out that democracy and republicanism originated in pantheistic cultures, while monotheism has always been implicitly monocultural. The Romans adopted Christianity as they were remaking the culture from the Republic to the Empire. When the West went back to less centralized political systems, it required a separation of church and state, culture and civics.

As for nihilism, without the ups and downs, it's a flatline anyway. Good and bad are not some cosmic conflict between the forces of righteousness and evil, but the basic biological binary of beneficial and detrimental. What's good for the fox, is bad for the chicken and when we assume good as transcendent, rather than elemental, all the higher order complexity, nuance and subjectivity gets washed out, in a race to the bottom, of good versus bad, aka, us versus them.

The Europeans were just in a funk, because modern technology changed the scale of warfare and they had to find out the hard way.

Logically a spiritual absolute would be the essence of sentience, from which we rise, not an ideal of wisdom and judgement, from which we fell. While it might be politically convenient to worship the big guy on top, the philosophers should have pointed out ideals are not absolutes and treating them as such only validates the truly fanatic.

Frankly the last couple thousand years of Western philosophy has been an abject failure.