Gay people can take credit for many of humanity's greatest accomplishments: the Sistine chapel, the invention of computer science, Glee. But according to Lord Carey, the former Archbishop of Canterbury, another achievement is imminent: the destruction of marriage. Yes, he argued yesterday, if you let gays get hitched they will "fatally weaken" the institution.

But when it comes to the ruination of marriage, I am all too aware of one undeniable reality: heterosexuals have beaten us to it. The facts, of course, have been discarded by Carey and his new "Coalition for Marriage". Since 2005, when civil partnerships were introduced, only 2.3 per cent have ended in dissolution. Far from harming marriage, civil partnerships set an example – in five of these years the divorce rate for heterosexuals went down. And yet, fewer straight people want to wed than ever before.

Why has this crisis in marriage already happened? Heterosexual men have poisoned the brand. Until 1991, husbands could legally rape their wives. Until 1882, a woman's property automatically became the possession of her husband. Until the 1960s middle-class married women were expected to give up work. Marriage was socially enforced. Cohabiting couples were despised as "living in sin". Single women were "spinsters". Single mothers were "sluts", sent to asylums or distant relatives, ostracised or institutionalised, and robbed of their newborn.

Marriage, when viewed in its complete historical context, does not look like a vehicle for love, but an instrument of control.

No wonder conservatives blame feminism for harming marriage; they are right, it has, by exposing all this, and we should be eternally grateful. Women now instigate twice the number of divorces as men.

To destroy a brand, however, takes more than systematic abuse. It takes derision. Celebrities ridicule marriage with such bravura it is profoundly remiss of Anglicans to allow them to book churches. Britney Spears marrying for 55 hours? Kim Kardashian marrying for a TV special? Anglicanism was created so Henry VIII could divorce yet its leaders have the temerity to accuse gays of "weakening" marriage?

As marriage declines, those who want to protect it should be begging gay people to wed. For we can offer a priceless gift: detoxification. How many sham civil partnerships have you heard about? How many gay bigamists have been exposed?

In the end I am reminded of Eminem's position. He knows about undermining the institution, given his second marriage, to the same woman, lasted 11 months: "Everyone should have the chance to be equally miserable."