People are not becoming less religious and more scientous, but they have become less religious in the past century, a century in which they have replaced religiousness-as-worship with something else.

No, people have never become "less religious", especially since they replaced religion with something else, that something else being simply: a belief in a different set of ideals, more materialistic, yet more unattainable even than "nirvana" or "God" or what other metaphysicals have you. A set of "post-"religious beliefs, of course, "rationalistic", and so on and so forth, a belief in technology and other entirely uninteresting carved images (and in any case, not even close to the Christian ones).

That can only mean that rough times, or rather "dark ages" are coming, and in these dark times people will be more and more susceptible to irrational arguments.

"People", that is, bipedal monkeys, have always been susceptible to "irrational arguments". The whole fucking premise of the sexual revolution was "irrational", if by "irrational" you mean "rational from false premises". No, I won't give another example, look for it yourself.

in order to appeal to the irrational, but more rational than two thousand years ago mind

Oh man, I won't even.

Yes, the so-called "dark ages" have come. But it will be yet some time of death, famine, pestilence and so on and so forth until these poor souls will be forgiven.