Earlier quoted context omitted.
That's a red herring, almost concern troll-esque, argument. This ruling isn't a slippery slope towards moral depravity and chaos, no matter how much religious authorities will attempt to paint it as such. We can definitely know that civilization as we know it will not collapse because two guys/girls are allowed to kiss, hold hands once in a while, and receive acknowledgment from civil authorities that they share tax…
The religious arguments made by opponents to this are disingenuous. The Bible and many other traditional religious texts have lots of bad things to say about, say, usury (the charging of interest, or at least excess interest), yet you see nobody protesting outside credit card companies or payday lenders. I don't think I've ever heard a Christian conservative criticize our excessive level of private debt. The Catholic…
But I don't think the real issue is crypto-racism. I mean, for one, I'm what you'd call a "racist" and I don't mention such to my anti-gay marriage family. I mean, hey, if racists and homophobes are all one big happy family, they'd know it, right? All I can say is that I'd advise you to take it in good faith when someone says they're against gay marriage and abhor racism. I'm not one of those people, but I used to be, and there are many of them.
(Another way you can tell: when conservatives parody protected classes by assigning as many statuses as they can think of, often they will come up with the black disabled lesbian with a liberal arts degree. But that would be an object of glee rather than outrage for the person you describe: the suicidal enemy. That conservatives don't like the BDL tells me that they don't really consider the homosexual part (or the degree!) a handicap. That's a victory, of a sort, for someone)
But I do think you're right that it's a proxy debate. I think it's an attempt to re-fight the sexual revolution, and gay marriage is seen as yet more lost ground on that front.
Was this a viable political strategy? Intuitively no, and empirically, definitely no. But voters gonna vote.