Proposing that homosexuals seek to destroy marriage by wanting to be married), and also seek to destroy democracy, seems more than a bit far-fetched.

I suppose they would destroy democracy by voting for an anti-democracy party in an election? These people just don't get it.

It's good to see someone trying to raise the intellectual bar on this issue, albeit the "irony" Christensen points to is more like petty equivocation rather than weighty thinking, depending as it does on the clause that <Their everyday cause is divisive identity politics, [and] not the unifying transcendence of love.>
"Twould be nice if that were so, and it ought to be according to queer theory, but sadly, in my view, it isn't. I think gay marriage is more often than not precisely, and merely, about love (I won't say "unifying transcendence of love" because that's a crock appertaining to gay or straight love!).
And this brings me to the real conservative vacuity of Christensen's position, as I understand it. He sees our "mature democracy" as somehow accomplished and its advocates as in a position to be "metaphysically subtle", apropos love and marriage, when as an institution it's always been an apogee of vulgarity.
More to the point, these conjugal connoisseurs can wax lyrical about the profundity of the marriage vowel, yet be utterly wooden, unreflective and uncritical of the crass and disingenuousness State they worship, that underwrites it.

The case for gay marriage does not rest on the qualitative effect of marriage on the relationship between two people. To some extend I agree with the author – the personal and spiritual dimensions of a relationship are not determined by whether the people concerned are married. Marriage is a symbol and affirmation of the unity of a couple; it does not constitute or guarantee that unity.

But, marriage is primarily a social construct. If gay marriage is outlawed, gays are debarred from the social, legal and moral recognition that society gives a married couple. An unmarried straight couple could choose to marry if they wish; a gay couple is permanently debarred from any possibility of having their relationship acknowledge and recognised in this way. To describe gay relationships as socially equal to heterosexual marriage in every way but the possibility of calling them marriage, must inevitably in my view mean that they are not really equal at all.

If only opposite-sex couples were allowed by law to buy cheese, rent DVDs or perform karaoke in public, then someone like Mark would be busily writing articles about how and why these activities have a cosmic significance, and warning us that homosexual participation in the profound ritual of DVD rental would break down the foundations of civilization as we know it.

How much more of this tedious homophobia in the form of faked-up concern for 'democracy' or 'marriage' or 'children' do we have to put up with? Why can't Mark and others just admit that a) they find homosexuality repellent, b) God forbids it, and c) that neither of these factors have anything to do with the fair allocation of human rights? Then we can get on with changing the law.

McReal.
There's a clear distinction between homosexuality and the Gay Liberation movement.
The term Gay itself in it's 19th century colloquial form referred to the louche, the outsider, the sexual transgressors such as homosexuals, prostitutes, the hustlers and deviants.
The term "Gay" was adopted by the movement which was a mere tactical change as the result of Marxist revisionism.
The Gay movement is a Left cause but we know that the Left always pushes forward it's trivial and unworkable or unrealistic pie in the sky causes to capture the attention of the gullible masses however beneath the fluff is the hard grey bedrock of Socialism, the Police state terror, the concentration camps, the grinding misery of the state farm and factory.
It's fair comment to point these things out but it'd be up to the Homosexual community to repudiate the links to and suppress the intervention of hard Left groups in what is essentially a trivial upper middle class political issue.