Explain to me how it is Halal in Islam to do this.
Because there is nothing in the Quran that actually
forbids it. What is not explicitly forbidden is therefore HALAL.
My understanding is that even back in the days, child marriage was very rare and generally frowned upon.
You are "understanding" incorrectly, probably because you are seeing it from a propagandized modern Western Cultural Marxist perspective, rather than a genuinely historical one free of the attitudinal baggage of modern day Totalitaria. There is no evidence to also show that "child marriage" was "generally" frowned upon in the past. There no doubt may have been
some who frowned upon it, in just the same way that anything else imaginable in existence might have been frowned upon
by some to some degree or other at any point in history. I think that if we look at the phrase "child marriage", while it has become a loaded cliché in these modern times (to which feminists have a complete meltdown over every time they hear of its occurrence), it would however not have been something even conceptualized by most people of the past. It would have been seen first and foremost simply as a marriage per se, and whether or not there may have been a
child in any given marriage would have been seen by most as something pretty well irrelevant, in much the same way as "child chess player" doesn't really hold any negatively loaded connotation today. Most people just think "Well, he's a chess player... so what?"
I think any historian who is being truly honest without allowing any modern day negative sensibilities and biases to influence him would admit that it would be drawing a very long bow to assert that "child marriage" would have been "frowned upon by most" in past times. But rather it would have been a quite
small minority who would have not felt positive or at least indifferent about the idea of child marriage. And if you want to go into all the history about it, you will find that child marriage wasn't "very rare" at all. It was, in fact, quite common, and even very common to the extent that it was more the
norm in some civilizations.
There is a Quranic command (4:59) to abide by the laws of the land you are currently living in, providing that they don't require you to commit a sin. So, if you live in a country where there is a law that says "no marriage under the age of XX" and you disobey that law, then you are NOT following Islam.
Believe it or not, I would have to agree with that actually. Often I have myself reminded Muslims that they should not reside in any kuffar countries because to live with the kuffar is itself against Islamic teachings. Note well that I did say previously that anything illegal in kuffar lands I will refrain from. This is why I said that I will only allow my daughters to marry in a jurisdiction where their marriage is not actually illegal. So yes, do in Rome as the Romans do, but while outside of Rome (and therefore outside of Roman jurisdiction), do whatever the other jurisdictions allow.
