The real turning point between the medieval age of faith and the modern age of unfaith came when scientists of the seventeenth century turned their backs upon what used to be called "final causes"...[belief in which] was not the invention of Christianity [but] was basic to the whole of Western civilization, whether in the ancient pagan world or in Christendom, from the time of Socrates to the rise of science in the seventeenth century....They did this on the [basis that] inquiry into purposes is useless for what science aims at: namely, the prediction and control of events.On one point I would wish to quibble with Stace's summary. He writes in the penultimate paragraph above that, "If our moral rules do not proceed from something outside us in the nature of the universe - whether we say it is God or simply the universe itself - then they must be our own inventions."
....The conception of purpose in the world was ignored and frowned upon. This, though silent and almost unnoticed, was the greatest revolution in human history, far outweighing in importance any of the political revolutions whose thunder has reverberated around the world....
The world, according to this new picture, is purposeless, senseless, meaningless. Nature is nothing but matter in motion. The motions of matter are governed, not by any purpose, but by blind forces and laws....[But] if the scheme of things is purposeless and meaningless, then the life of man is purposeless and meaningless too. Everything is futile, all effort is in the end worthless. A man may, of course, still pursue disconnected ends - money, fame, art, science - and may gain pleasure from them. But his life is hollow at the center.
Hence, the dissatisfied, disillusioned, restless spirit of modern man....Along with the ruin of the religious vision there went the ruin of moral principles and indeed of all values....If our moral rules do not proceed from something outside us in the nature of the universe - whether we say it is God or simply the universe itself - then they must be our own inventions.
Thus it came to be believed that moral rules must be merely an expression of our own likes and dislikes. But likes and dislikes are notoriously variable. What pleases one man, people, or culture, displeases another. Therefore, morals are wholly relative.
I think, however, that if our moral rules derive from the universe they're no more binding or authoritative than if they are our own inventions. The only thing that can impose a moral duty is a personal being, and the only being that has the authority and ability to impose an objective moral duty is one that transcends human finitude. Neither the universe nor any entity comprised of other humans qualifies.
Unless God exists there simply are no objective moral duties. Thus, if one believes we all have a duty to be kind rather than cruel, to refrain from, say, rape or child abuse or other forms of violence, then one must either accept that God exists or explain how such obligations can exist in a world where man is simply the product of blind, impersonal forces, plus chance, plus time.
Put simply, in the world of Darwinian naturalism, no grounds exist for saying that hurting people is wrong. Indeed, no grounds exist for saying anything is wrong.
It's not just that modernity and the erosion of theistic belief in the West has led to moral relativism. It's that modernity and the concomitant loss of any genuine moral authority in the world leads ineluctably to moral nihilism.
This is one of the themes I present in my novel In the Absence of God which you can read about by clicking on the link at the top right of this page.