For example, people have to first intuit that all men are created equal before regarding inequality as problematic instead of just being in the nature of things. Legal equality is a discovery, not a given. And once discovered it needs to be real-ized in the world, for which reason the Constitution follows the Declaration as effect to cause.
The moral intuitions prompted by Christian beliefs provided just such a basis "for an appeal against injustice that had not been available in the ancient world" (Siedentop). Thus, "the universalism of Christian aspiration had a subversive potential" unknown to that time, and still at work in the world today.
You could say that the universal subverts the particular, just as in science, whereby a more general theory subsumes disparate phenomena: ice and clouds, for example, are just different states of water.
Against this progressive approach is the modern superstition of multiculturalism, whereby the particular subverts the universal: for the left there is no objective or universal good except for the conviction that there isn't. Except when there is. I know. It's a form of Gödel's theorems: you can get consistency or completeness from a leftist, but don't expect both.
Regarding the invention of progress, "The idea of a more 'open' future was a symptom of Christian moral beliefs affecting the population at large." This was accompanied by "the rejection of fate and advent of hope," but this cuts two ways, since the new uncertainty brings with it new anxieties.
As someone once said, if you have no alternatives then you have no problems. But the dawn of an open future that can be shaped by the individual brings with it a new burden of responsibility which some people, understandably, don't want to bear. Nowadays we call them liberals.
Today we talk about "upward mobility," but this was preceded by awareness of a new inward mobility. As Siedentop writes, people began realizing "that salvation did not depend upon social status," which contributed to a new "kind of imagined mobility, a moral standing that could be achieved rather than inherited."
Now, here's an ironic one: a critically important factor in the development of a common European identity was the contrast with a violent and expansionist Islam. The presence of a common enemy can cause people to appreciate a shared identity.
For example, leftists everywhere are proclaiming that "I am Charlie Hebdo." But it shouldn't take a mass murder for leftists to realize that they too are nihilistic peddlers of pornography, only more craven.
A better example is their universal hatred of Fox News, which is the only major media outlet that actually does critique Islam, only in a far more informative and measured way than Charlie Hebdo.
But you will never see hypocritical leftists proclaiming I AM RUPERT MURDOCH!, because their identity depends upon this shared hatred of conservative heresy. They will shout I AM ISIS! before admitting any common values with conservative liberalism (as Jane Fonda might just as well have announced I AM HO CHI MINH!, or Jimmy Carter I AM YASSER ARAFAT!)
Back when religious leaders weren't appeasement-mongering invertebrates, "The appeal by Pope Urban II for volunteers to halt the expansion of Islam... created in Europe a new consciousness of itself." Prior to this, "Europe had never been excited by one sentiment, or acted in one cause; there was no Europe. The crusades revealed Christian Europe."
No wonder leftists can't forgive the crusades and Muslims can't forget them.
Once again Islamic terrorists are trying their best to bring about a unified response, but leaders such as Obama refuse to even name the enemy, for it would engender the wrong kind of unity, i.e., a patriotic love for our way of life.
Rather, Obama's leftist worldview revolves around despising our way of life, so in that sense he's implicitly in agreement with the terrorists. This is a guy who spent two decades in a toxic
mosque church that taught exactly this doctrine, i.e., GOD DAMN AMERICA! and all the rest. Terror is just leftism by other means.
So, "The crusades were truly a universal event, involving all strata of the population," revealing "'a people' with a shared identity."
Again, this is very much in contrast to the reigning dogma of multiculturalism, whereby the only thing that unites us is our differences (along with an unacknowledged, implicit unity derived from hatred of universalist conservatives).
If Islamists had wanted to invent a divide-and-conquer strategy, they couldn't possibly have come up with something more effective than this principled divisiveness of the left.