The gay-rights brigade have allowed their quest for gay marriage to tip over into active hetero-phobia. If they don't snap out of it, they'll even lose the support of gay people like me.

A little while ago I wrote a piece for ConservativeHome about how the attacks and smears of the pro gay marriage campaign had shaken my belief in the cause to its foundations. The impulse to cry 'paedo' every time a Catholic spoke of their discomfort over same sex marriage, the howls of 'bigot' accompanying even the most gentle warning about potential implications - these are the characteristics of a movement that no longer believes it can win an argument and has instead decided to rely on ad hominem and vitriol. It is intolerant and it is ugly.

Over the last week we have seen further examples of the extent to which the gay rights militia has abandoned any moral authority and now seeks, apparently unashamedly, not to win through debate but to rob others of their right to speak.

First came the Advertising Standards Authority's demand that the blogger 'Archbishop Cranmer' answer for the adverts he had run on behalf of the Coalition for Marriage campaign. These ads - which showed heterosexual couples celebrating their nuptials and implored viewers to sign the coalition's petition - apparently caused 'hurt and offence' to some gay people. The only way in which one could possibly be 'hurt' by the ad would be if one were somehow offended by the image of straight couples doing what straight couples have done for thousands of years - marrying one another. This isn't a reaction against 'hate speech' folks, it's outright hetero-phobia.

These readers responded to their 'hurt' not by engaging in debate or navigating away from the page but by submitting complaints to the ASA - who have followed up in aggressive style and have frightened the man behind the avatar into hiring in the lawyers.

Next came the extraordinary decision by the Law Society to withdraw permission for an event on the role of heterosexual marriage in a good and just society. Cristina Odone (who was due to speak at the event alongside my friend Phillip Blond) has written for the Telegraph that the decision was taken on the basis that a discussion of heterosexual marriage contravened the esteemed society's 'diversity policy'. Apparently diversity - for the Law Society at least - stretches only one way in the discussion of public policy.

And this is the problem. I too believe in diversity. I'm a gay man (who, as it happens, believes that gay marriage is the right way forward for our society) who has benefited from our tradition of allowing a plurality of views and for the open discussion of what is good and right and what is bad and wrong. Were it not for Britain's tolerance of dissent who would have been brave, or foolish, enough to argue that people like me ought not be imprisoned for our sexual desires?

Yet that very word, 'diversity', has now come to represent not plurality but homogeneity, not dissent but repression. Hiding behind it, secularists and the ayatollahs of social liberalism are able to strip public discourse of the bits they don't like - faith, orthodoxy, skepticism about change. They have been able to use the frame of diversity as a weapon against its very purpose; to shut out and shut up those with whom they disagree.

It's time for those gay men and women who genuinely prize freedom to take a stand against those who act against it in our name. It is up to us to continue winning the argument for the freedoms our society permits us - not to preserve those freedoms at the expense of others' consciences or right to speak.

If my society gives me the right to marry I want that right to have sprung from a collective judgment, not from the authoritarian zeal of those acting, supposedly, on my behalf. Let's leave the hetero-phobia at the door and get on with the business of political and moral debate. For goodness sake gays, stop whinging about people who disagree with you - argue with them.

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