The UK government has committed itself to marriage reform to include same-sex couples. It was an obvious and largely uncontested announcement...until a new and secretive coalition of fundamentalist organisations whipped up an artificial storm.

The planned introduction of same-sex civil marriage to the UK was considered such a trivial extension of current 'civil partnership' legislation, such a clear and just moral claim, that it could be introduced by a Conservative-led coalition government to applause from the great majority of Conservative MPs.

The proposals received but a smattering of media attention, and a polite welcome from LGBT groups. 'Separate but equal' legislation would be a thing of the past. The final, uncontroversial baby-step toward equality was underway.

But since February this year, a well-oiled PR campaign against the proposals has been busy giving the false impression of a public backlash to the proposals.

It does not alter the moral equation a jot, nor (we hope) has it had a serious impact on public support for progress and equality. However, it is worth considering exactly how a small cartel of fundamentalist Christian groups, unrepresentative of the vast majority of the UK, including most ordinary Christians, could create such a media footprint in such a short time.

The Coalition for Marriage (C4M) is a network of evangelical Christian groups in the UK (the kind often described as "US-style", not without reason). The exact composition of this coalition is not advertised on their website. However a bit of digging unearths a few quite extreme organisations (more extreme than any mainstream UK church, anyway).

One of C4M's members is the Christian Institute, a group who are almost single-handedly responsible for a PR campaign spanning several years in which a handful of employment tribunals against Christians (usually demanding privileges or refusing to treat gay people respectfully) are endlessly recycled and cross-referenced into a media-friendly narrative about "Christian persecution". Another of their members is the fundamentalist group Christian Medical Fellowship, which campaigns against women's choice over abortion rights, and welcomes good Christian doctors as long as they believe "The Bible, as originally given, is the inspired and infallible Word of God."

The Coalition for Marriage (ironically so called, given their mission is to fight marriage for some people) has conducted a two-faced campaign of misdirection, unrepresentative of public opinion while claiming to be so. They say they want a national debate. What they're actually offering is a US-style PR campaign against equality for LGBT people.

C4M is countered by the Coalition for Equal Marriage (C4EM), which we brought together as a response, to support and defend the equality proposals.

The equal marriage side advertises its organisational members rather more proudly than C4M. Our members include religious groups and denominations in favour of marriage reform, as well as secular and humanist groups, the top three political parties' LGBT groups, gay rights campaigners such as Stonewall, and LGBT media such as Pink News, Attitude magazine, Gay Times magazine and the Gaydar group.

We'd welcome a debate with C4M, as they claim to want. What we have instead is ex-archbishops and cardinals marching to an evangelical tune like puppets, offering no argument and no evidence for extraordinary claims about how same-sex marriage will compromise parenthood and bring down society.

Evidence from 10 countries that have already introduced same-sex marriage suggests that fears about the imminent collapse of civilisation are somewhat exaggerated. Rates of dissolution for the first five years of (same-sex) civil partnerships in the UK are significantly lower than rates of divorce for (heterosexual) marriage over the same period. Whatever else this indicates, it at least suggests that same-sex couples are neither constitutionally incapable nor un-desirous of long-term commitment.

A letter presented to all Catholic congregations in UK churches last month claimed that if same-sex couples were allowed to marry, "There would be no recognition of the complementarity of male and female or that marriage is intended for the procreation and education of children." Do they really think that heterosexual couples will stop recognising the opposite sex, stop falling in love, or start falling out of love, if same-sex couples can marry? Do they think the maternal and paternal (and various related) natural instincts of human beings will dissipate if they know that some gay people are allowed to marry? C4M might respond that that's not what failing to recognise "the complementarity of male and female" means... but then what does it mean, in any practical sense?

Theirs is a campaign of distortions, fear, and the kind of creeping inversion that actually can propagandise minds:

• We're no longer a loving couple - we're a "lobby".
• They say they're "defending traditional marriage" - all they appear to mean is they're defending the exclusive ringfencing of marriage for heterosexual couples alone.
• A small number of fundamentalists campaigning to deny sexual minorities a freedom which they themselves enjoy, is inverted such that sexual minorities are forcing everyone else to change (change what? Will my marriage affect yours? You'll break up as a result? What?)

At the centre of this vortex of rhetorical distortion is religion: religion being used as a weapon to attack a purely secular, civil proposal. The Coalition for Marriage PR campaign talks up tradition, uses high-profile Church figures as mouthpieces, and encourages congregations directly to sign their petition, and strangely enough it has given many religious people the impression that their churches will be affected. This is wrong and it must be corrected. The proposals for same-sex marriage encompass only civil ceremonies. Far from forcing churches to conduct same-sex marriage, the government has said it is not proposing even to allow same-sex religious marriages.

(We do by the way think that churches who want to conduct same-sex marriages should have that religious freedom. Religious same-sex marriages are explicitly not proposed in the consultation but the government is asking about it. Even if civil same-sex marriage and opt-in religious same-sex marriage is allowed, consecutive governments on either side of the political spectrum have assured religious groups that they won't be forced to conduct them. Still C4M insist that it's only a matter of time before vicars are frog-marched into church to conduct them. Who exactly would want to be married by a hostile celebrant anyway?)

C4M says that equal marriage is about a minority 'redefining' marriage for everyone. They use this word 'redefine' over and over again, like a mantra. And it's obtuse. There will be absolutely zero change to the way a man and a woman would get married in a registry office, or in a church. The act of marriage itself will be the same. We will simply have a few new kinds of couple being included and being equal.

Changing the exact applicability of a word does not fundamentally redefine it.

We don't want to change marriage, we want to be part of it.

The anti-equality campaign also insists that government has no mandate to open up marriage to include sexual minorities. Given C4M's very religious motivations, and the fact that religious marriages made up no more than 30% of all marriages back in 2009, we would say that C4M are the ones who have no mandate to presume to speak for the country. With 70% of marriages in the UK being without religion at all, and with even religious marriages needing to be recognised by the state, the government not only has every right, but has an obligation to open up marriage and end discriminatory gender restrictions.

In reality same-sex marriage is not unpopular in the British population, and same-sex couples and their friends and families very often refer already to their unions as being 'married', because that's how they think of it.

C4M claim they're a grassroots organisation. They are not. That would mean starting with ordinary people. How is an organisation that was launched by a former Archbishop of Canterbury, with a petition pre-signed by bishops and Anglican Lords and right-wing MPs, and a campaign with PR support from well-oiled, unrepresentative fundamentalist groups ever a 'grassroots' campaign?

In actuality the church's worst-kept secret is that most ordinary Christians, even many of the clergy, are in favour of gay rights including same-sex marriage. C4M appear to have a lot of signatories, but that doesn't show online - the pro-equality side have more support on social networks for example.

And through that medium we're being told of people feeling pressured into signing C4M's printed petitions in nursery schools and churches (one Twitter follower even told us of people duplicating signatures online and in church).

The anti-equality lobby has manufactured a false public opinion by commissioning polls full of weasel words and then claiming that the majority support them, even though their polls mysteriously avoid asking people the central question on the agenda: Do you agree same-sex couples should be able to have a civil marriage in a register office? Meanwhile every reputable poll which does ask directly, shows that the British public do support equality and inclusion on this issue.

We're actually at a juncture in UK history where the Lesbian and Gay Christian Movement better represents the ordinary Christian's view on equality than do the fundamentalists behind Coalition for Marriage. (A recent RDFRS poll with Ipsos/Mori found that the majority of Christians, 61%, "agree that homosexuals should have the same legal rights in all aspects of their lives as heterosexuals".)

That is brilliant, and it is welcome, and it must be embraced. The Coalition for Marriage not only have no mandate to speak for the country, they have no mandate to speak even for Christians.

Follow Conor Marron on Twitter: www.twitter.com/C4EqualMarriage