Before the new philosophy of the seventeenth century, European thinkers had looked on the world of nature as sharply divided by the boundary between the heavens and the earth. In the physical heavens and the celestial bodies, there was regularity and order, though this was not expressed in terms of law: astronomy was the one dignified area of natural inquiry for a learned mind. Beneath the moon, however, chaos reigned: disorder, instability, and disharmony. God's providence extended to the whole of the creation, but beneath the moon, it was above all in terms of His particular acts of will that He governed. The ongoing motions of the heavenly bodies alone seemed to bear the imprint of a more general providence. All of this changed in the aftermath of the seventeenth century.
From an article about the Enlightenment, and the progression of thought among European Christians.
Christ Church Quadrangle, Oxford. Man, for an atheist blog I sure put a lot of church pictures on here.
The real meat of the article is about the resulting shift in moral thinking (the discussion of Voltaire's Letters shows how he anticipated a lot of later developments) but from the quote above, there are two implications:
1) As culture and the world get "tamed" and regular-ized - that is, as civilized life becomes more predictable (and we have more records of what's gone on before so we can see more patterns) - the world is more obviously a place subject to similar kinds of rules as we can observe in the heavens. It's no longer the hopeless mess that it was throughout all of previous history. And indeed, when Gibbon first argued in The Decline and Fall of the Roman Empire that the Rome fell for purely secular, material economic and political reasons, he provoked an outcry that would be surpassed only by that for Marx's and Darwin's work in the following century. As people turn to more rational ways of making their way in the world, conditions improve and regularize; people become more rational; conditions improve; etc. (In the Post-American World Fareed Zakaria makes a similar argument for the use of clocks and measuring devices for driving economic growth in Europe prior to the industrial revolution.)
2) As more of the world becomes understandable in terms of natural law, rather than the eternally incomprehensible product of God's interference, it becomes harder to find corners of ignorance to hide in. It may be for this reason that studying psychology, anthropology or linguistics are more highly associated with loss of religious attitudes during undergraduate years than the hard sciences. Explaining our minute-to-minute experience in these terms may be religion's worst nightmare, and the backlash against neuroscience is already starting.
Of course it's undeniable that the Christian universities and people of Europe began and sustained the Enlightenment, a fact which educated Christians rightly point out. But did the Enlightenment happen because of Christianity? If so, why did it take seventeen centuries (or thereabouts) to get off the ground? Certainly there have been flowerings of technology and economics elsewhere in the world not owing a thing to Christianity. The same argument applies to slavery: if it's Christianity that was the proximate cause, why did it take eighteen centuries for Christians to figure out that it was wrong? Especially since it took the Enlightenment only one.