We kind of paint this idealized view of the past when in reality, we would recognize very little of it. Marriage is just once example. Our concept of marriage, as a mutual choice, out of love, before God and the State, is rather a new concept. While in many cases across many cultures, it was a religious institution, it more often than not, was political or financial and arranged.
You're right. It's not so very long ago that a prospective husband was expected to ask the bride's father for her hand in marriage -- something with a long history. The practicalities of that are various, but it includes ensuring that the daughter and her offspring would be well provided for, and also that the effective merger of the two families was advantageous. Along those lines, arranged marriages were common among the English aristocracy until ... maybe WW1. When there's property and money and influence involved, such things tend to matter at least as much as romance.
OTOH, I've long suspected that the romantic aspects of marriage have always been more common among the lower classes, where much less is at stake materially. Even then, however, the need for the daughter to be provided for is a natural concern of her parents.
I don't bring this up to mock marriage but to point out something we all need to think about which is to separate the government from our sacrament. When it was a political rule in the Bible (versus a personal commitment), the rules were wide and varied.
That said, there's a broad overlap between the sacramental and legal aspects of marriage. We'll never truly be able to separate them, because marriage is not only a religious thing -- it's lived out in the world, with all that implies.
The thing about the Bible is that it's really practical about a lot of things, marriage being one of them. Jesus' description of marriage in Mark Chapter 10, for example, is as concise a discussion of marriage as you'll find anywhere. When you look at it, there are very real and practical social benefits to the "one flesh" aspect of marriage -- a good marriage tends to make for good kids and law-abiding men, for example. To promise before God, strengthens the meaning of the sacrament. (And, of course, it's
of God....)
So, too, in secular society, there is an obvious public interest in protecting and promoting traditional marriage as best we can: research from across the political spectrum has shown that the mess of the inner city is in large part statistically explained by the absence of married, biological parents. And when a marriage goes wrong, there are legal consequences having to do with distribution of property, ensuring that children are properly provided for, and so on.
Where government/religious separation can and should be maintained, is in the area of what the law requires of churches as regards marriage -- the law must never say what a Church can and cannot consider to be "marriage."
