In recent days the debate over equality in marriage for same-sex couples has been marked by inflammatory and derogatory remarks by vocal opponents, the Catholic Cardinal Keith O’Brien and his apparent echo, the newly UKIP MEP Roger Helmer.

We don’t need to waste much time on Helmer. Suffice it to say that, contrary to Nigel Farage’s claim that Helmer’s defection from the Tories to UKIP means people are taking the latter seriously, it just demonstrates that UKIP are even more of a bad joke than ever. The party is a refuge for nasty extremists, and welcoming their newest recruit just shows their true colours.

From the other side of the fence, I’m delighted to say we have heard good sense not only (of course!) from LibDems but also from Conservatives like Francis Maude and Eric Pickles and from the Anglican former Bishop of Oxford Lord Harries as well as the Prime Minister.

Liberal Democrats have a strong record of advancing and campaigning for equal rights, and we are whole-hearted supporters of equal marriage. With Liberal Democrats as part of the Coalition, and Lynne Featherstone in the Home Office as minister for equality, this government is committed to advancing equality for lesbian, gay, bisexual and transgender people. We say of equal marriage: ‘it is no longer a question of whether – it is when’.

We believe that people should be free to express their love publicly and through marriage regardless of their sexual orientation.

Lynne Featherstone has urged that the debate should not be polarised and the proponents of equal marriage have heeded that advice; I’m not aware of any frenzy of invective against opponents! Even those of us like myself who are nonreligious have declared respect for the views of those who sincerely believe their religious faith prevents them from advocating or endorsing marriage other than between a man and a woman.

That is precisely why there is no suggestion from any quarter that religious bodies should be forced to hold same-sex marriage ceremonies. This policy is about removing a state ban on gay people having a civil marriage. Draft legislation is not of course available yet, but for such a civil ceremony I would expect the law to apply as upheld so far in the courts in regard to civil partnerships, namely that a registrar cannot invoke faith as a pretext for discrimination.

In contrast to this reasonable and sober approach by equality advocates, the arguments against gay marriage have been deployed in torrid style. Cardinal Keith O’Brien echoed by his cheerleader the newly UKIP MEP Roger Helmer, labels same-sex marriage as ‘madness’, ‘a grotesque subversion’. He said its ‘immorality’ matched that of slavery and outrageously bracketed it with incest and (interesting variations on) polygamy. I have called this ‘scraping the barrel of prejudice with no foundation whatsoever’.

Even the right-wing commentator on the Daily Mail, Stephen Glover, who objects to David Cameron’s support for equal marriage, believes that O’Brien’s language was ‘perhaps over the top’. You can say that again! The very fact that those opposed to same-sex marriage cannot have a reasoned debate about the issue just proves that they are bereft of any real arguments.

As woman married (to a man) for almost 30 years and fortunate enough to have had the example of my parents who had almost 50 years of marriage until my father’s death, I am hardly out to destroy the institution of marriage. So I strongly refute Cardinal O’Brien’s assertion that the aim is ‘to redefine marriage for the whole of society at the behest of a small minority of activists.’

There is no ‘redefinition’ of marriage going on. It will still mean two people wishing to make a public legal commitment to each other, with all the benefits as well as obligations that marriage entails. I have gay friends who have been in partnerships as long as I have. How exactly might their wish to emulate my married state threaten my marriage?

I do in fact agree with Cardinal O’Brien that the institution of marriage is one of the fundamental building blocks of society. But equal marriage does fulfil what he is asking for, that government ‘should act to protect and uphold marriage, not attack or dismantle it’. The widespread support for LGBT couples to have access to marriage is because of the realisation that, far from weakening marriage, inclusiveness will strengthen it.

But the experience of marriage also evolves over time. As Lynne has said, marriage is ‘owned’ neither by the state nor by the churches (or mosques or synagogues). It is owned by the people. And it will be shaped by what people want to make of it. For example, most heterosexual couples long ago jettisoned the non-reciprocal ‘I obey’ pledge made by the woman to the man. This reflected the ‘patriarchal baggage’ that I referred to in the Lords second reading debate on civil partnerships a decade ago.

Equality has a habit of refreshing the parts that dead tradition cannot reach.

And the fact that the Helmers of this world have felt stranded as the Conservative party modernised is an excellent sign. It shows that the Tories, at least at the top, are changing and that backward and bigoted views are no longer welcome in mainstream politics.

So the debate is not about religious rights versus gay rights; it’s about human rights. Every person should have the right to marry the person they love, whether male, female or transgender, gay, straight or bisexual.

I fully support the the Coalition for Equal Marriage and strongly urge people to sign up to their petition. I am proud that the LGBT+ LibDems, of which I am a vice-president, were one of the first partners in this group. As LGBT+LD Chair Adrian Trett said, “the Liberal Democrats are the first and only major party to support marriage equality”.

Liberals are also the only major political force in Europe that offers unwavering support to Europe’s LGBT citizens. I hope the Tory and Labour parties as a whole, not just the leadership, will join us.

So I eagerly await the Coalition’s consultation on equal civil marriage, due out this month, and urge as many people as possible to respond positively. It is about time that support is heard loud and clear above the clamour of extremist views coming from the likes of some in the Churches – and UKIP.

Sarah Ludford is a Liberal Democrat Member of the European Parliament for London, the Liberal Democrat European justice and human rights spokespersn, a non-voting member of the House of Lords and vice president of LGBT+ Liberal Democrats.