I've addressed all your other points elsewhere in this thread, but the following is new:

> You're also characterizing this as a "vast" change. What is the vast change here?

That marriage should now be an institution open to homosexual couples as well as to heterosexual. Taken in isolation, it doesn't seem like a big deal to me, either. But nothing in society exists in isolation, and quite aside from the historical novelty of it, many millions of people regard this particular change as a very big, and very undesirable, deal indeed.

The impression I have is that those with whom I've argued the point here today see no reason to doubt that they know better than those many millions who share this opinion - so much better, in fact, that there's no point taking very seriously any argument, opinion, or belief, other than that which they themselves advance, espouse, or profess - or at least already agree with on all substantial points.

I was that confident once, too. Sometimes I miss it. But nothing is ever simple, and pretending otherwise can make fools of us all.