Re: You’re invited to a gay wedding..
No, the best logic is that Western countries are secular, and religion has no place in a civil union. All citizens should have the same rights.
One might oppose gay marriage because of their religious views, but would they not then be imposing their views on atheists or agnostics? Is that fair?
And if you’re against a secular country, then keep in mind that under a Christian theocracy none of us would be living in the West, and we would be persecuted and murdered.