I don't know, do today's books and newspapers relect the average man? True that the educated men of the time were either nobility or clergy. But the churches were filled with average men and women who learned from those clergy. Not to mention that the first schools were started by those clergy.
I believe that mans ethos has evolved, along with societies. Of course the ethos have changed, but that is because man has. I believe, though, that men still hold those same things dear to him now, that they did then.
Evolved? If you consider neo-barbarianism evolving then okay. I disagree. During those so-called dark ages the average man held God and Church above state; today, the State holds the position of supremacy.
If God's truth were universal, then why don't all men believe the same?
If facts are universal, why don't all men believe the same? Because man has a fallen nature and has an unfortunate tendency to pursue his own appetites than aknowledge an uncomfortable universal truth.
Again, if truth is not universal then how is communication possible?
I think that today, books and writings are so much more prevalent, that they do reflect the average man more, just by default and the fact that there are so many more.
I don't really know what neo-barbarianism is. During the dark ages, men also were much more superstitious.
I believe that facts, such as temperature, gravity, etc, are believed by probably >99% of people, throughout history. If someone held up 2 fingers on each hand, I believe that any normal person, would be able to understand that holding up 4 fingers on one hand, equals that amount, or that things drop when released. These sort of things are facts. Of course, there are always some that will disagree with this, but they are the extreme minority. We are talking about God's truth, not facts that can be proven. This is belief. This is why so many people disagree about those things, that cannot be proven...they believe differently, just as God intended.
You have no way of proving that man has a fallen nature. Man has a tendency to pursue his own appetites, because that is what man does, that is how we were created...by God. God knew what man was going to be like, before He even created us.
I don't know what you mean by your last line.