I like this passage of GK Chesterton's Orthodoxy. Incidentally Chesterton was born in Kensington where the driver rammed a bunch of pedestrians with his car. The keyest parts are highlighted. It takes a while to build a new civilization on new fundamentals. In terms of what Christianity was capable of civilizationally it was still quite in its infancy in the Late Roman Empire and Early Middle Ages. The primary cause of the "dark ages" was the decline of Roman Civilization, not Christianity dragging it down.
"I take in order the next instance offered: the idea that Christianity belongs to the dark ages. Here I did not satisfy myself with reading modern generalisations; I read a little history. And in history I found that Christianity, so far from belonging to the dark ages, was the one path across the dark ages that was not dark. It was a shining bridge connecting two shining civilisations. If any one says that the faith arose in ignorance and savagery the answer is simple: it didn't. It arose in the Mediterranean civilisation in the full summer of the Roman Empire. The world was swarming with sceptics, and pantheism was as plain as the sun, when Constantine nailed the cross to the mast. It is perfectly true that afterwards the ship sank; but it is far more extraordinary that the ship came up again: repainted and glittering, with the cross still at the top. This is the amazing thing the religion did: it turned a sunken ship into a submarine. The ark lived under the load of waters; after being buried under the débris of dynasties and clans, we arose and remembered Rome. If our faith had been a mere fad of the fading empire, fad would have followed fad in the twilight, and if the civilisation ever re-emerged (and many such have never re-emerged) it would have been under some new barbaric flag. But the Christian Church was the last life of the old society and was also the first life of the new. She took the people who were forgetting how to make an arch and she taught them to invent the Gothic arch. In a word, the most absurd thing that could be said of the Church is the thing we have all heard said of it. How can we say that the Church wishes to bring us back into the Dark Ages? The Church was the only thing that ever brought us out of them."
