The Quran stressing on the link between winds and clouds: rain

[robvalue]

I'll take a stab at the unspoken implication here.

The people who wrote this book "knew" things that they couldn't reasonably have known about at their point of scientific development (zero). This means that the information is likely to have come from an external source.

This wouldn't be too bad, if it was to stop there. It would better to just say we don't know how they "knew" these things, but I'll settle for the above. But we all know that the further implications are going to be:

Since their information source was right about this thing (and whatever other examples), we should trust the rest of what the book has to say too.

Nope. That is hopelessly flawed thinking. You're in a position where you'll literally believe anything this source says, about any subject. That is a total surrender of all scepticism. It's reasonable to have confidence in someone speaking about a certain field of which they have demonstrated a very firm grasp, but to extend that to every word they have to say is not justified.

At the very best, we could say that we have some confidence that everything the source says has some credibility and is worth looking into. But as we all know, when viewed without the lens of prior belief, all these books come off as exactly the kind of ramblings you'd expect from a primitive culture with zero scientific knowledge. It's guesswork at best, and those wanting to find meaning just fill in the blanks.

There's an even more fundamental error going on there.  They assume that because the person is right about something that they, presumably, shouldn't have had knowledge about, that it isn't simply unexplained, but rather that the source of their knowledge was an omniscient God.  Not only is this a non sequitur, but they are using this as the basis for believing other claims in the book, such as that Mohammed spoke to the angel Gabriel, based upon that non-sequitur, and using that as confirmation that the source of the things in the book was supernatural.  It's an incestuous little circle of one fallacious conclusion supporting another fallacious conclusion, which supports yet another fallacious conclusion, and so on.

You're absolutely right. The (broken) thinking is that a person producing the unexplained gets to explain it without question. Matt D made a good example of this. If a magician manages to "move" a card from one hand to the other, and you have no idea how it could have possibly have been done, he doesn't get to declare that he teleported the card.