The problem with the state’s involvement, at least in the modern era, is that the definition it uses to recognize the institution is simply whatever judges, pols or the majority thinks it is at any one time. And that’s it.
“Now, since the family and human society at large spring from marriage, these men will on no account allow matrimony to be the subject of the jurisdiction of the Church. Nay, they endeavor to deprive it of all holiness, and so bring it within the contracted sphere of those rights which, having been instituted by man, are ruled and administered by the civil jurisprudence of the community. Wherefore it necessarily follows that they attribute all power over marriage to civil rulers, and allow none whatever to the Church; and, when the Church exercises any such power, they think that she acts either by favor of the civil authority or to its injury. Now is the time, they say, for the heads of the State to vindicate their rights unflinchingly, and to do their best to settle all that relates to marriage according as to them seems good.”
—Pope Leo XIII about 130 years ago.
Freegards
Excellent quote! thank you for that.
Yes, by allowing the state to define marriage it becomes vulnerable to whatever changes the state makes.
But this is not the fault of the state, but the people who have come to run it. I still believe somehow that the state must be involved - otherwise, you will have a secular society with its own definitiosn, and a Church with different ones. Church and State cannot have that huge a gulf between them. Or so it seems to me.