Christianity is the world’s teacher, not its student. The world has nothing for us but lies or distortions, which are ignorance and death. Oddly, as objectionable as it might seem to claim that one group in history holds the truth, or was given the truth, or distributed the truth, even about the rest of the groups, it’s not particularly difficult to show historically.
Christ, through his Church, transformed the world. There were things toward which humanity and cultures and civilizations tended naturally. Then there was a long process whereby those natural inclinations were countered, and eventually changed. So much of humanity, culture, and civilization today is entirely unnatural. It would never have occurred naturally. And most of us prefer it to the alternative. (Although we sometimes are mistaken about history and therefore assume either that there is no difference, or that the alternative is better than it was.)
The most obvious example is human rights. If you like living in a world with human rights, you have Christ to thank. No purely natural society in the history of the world ever imagined anything like the claim that all human beings have value, just by virtue of being human beings. But Christ said they did, and Christians labored for centuries in the long (and often perilous) process of changing one of the natural world’s primary assumptions. And rather contrary to what might be expected, they largely succeeded. Now we tend to assume that it’s perfectly natural to imagine that people have some sort of intrinsic value. It is most certainly not natural; we have been taught.
And of course the Church did not stop there. It was the Church that taught the world that foreigners, strangers, slaves, and women were all human too, and thus were all immeasurably valuable in some sort of ontological sense, not just an expedient, social, or economic sense. If you like living in a world with civil rights, you have Christ to thank. No natural society ever imagined anything with which you would be at all comfortable.
And the Church did not stop there. It was the Church that taught the world that war was evil, not just inconvenient. The entire concept that war was almost always wrong and was only grudgingly excusable in certain extreme circumstances, that concept was taught to the world by Christians. The natural societies before Christ fought each other as a matter of course. It’s no surprise that the world before Christ was populated by empires rising and falling: conquest was the norm. Nobody questioned it. It’s also no surprise that nations couldn’t develop until after Christ. He needed to teach the world that peace arose not from mutual counterbalancing strength, but from mutual respect.
In fact, if you like the idea of respecting people who are different from you, you have Christ to thank. (People will sometimes talk about the Roman Empire as being a diverse and tolerant place, but not generally people who have studied the Roman Empire.)
I could go on, but I’m out of time. Here is one last point though. The world, having largely rejected the Church, is intent also on unlearning the lessons Christ came to teach the world. The world we find if we forget our tutelage will not be one we like. I suspect that eventually we will look around ourselves and realize that we made a mistake, and we will return to our teacher. It would likely be better for us not to leave in the first place.
Also, Christians need to be very careful about assuming that worldly cultural developments need to be applied to the Church. Naturally the world will attempt to twist and abandon the hard lessons that Christ came to teach, and it will do this in such a way as to seem wise itself. (Rather like the way teenagers will argue against the good advice of their parents.) But the world cannot instruct the Church on truth or goodness, it never could and never will. Christians ought to be examples to the world, not learn from it.