David Cameron placed great emphasis on two words when he told last year's Tory party conference that the government would hold a consultation on legalising gay marriage.
"Yes, it's about equality," he said, "but it's also about something else: commitment."
But nearly half a century after homosexual sex was decriminalised, more than a decade after age of sexual consent was equalised, and almost seven years after the first civil partnerships, there remain profound suspicions on both sides about the precise nature of the state's commitment.
Equal rights campaigners point out that the consultation will not touch on the ban on same-sex religious marriages, nor the prohibition on heterosexual civil partnerships.
The Church of England and the Roman Catholic church, meanwhile, cannot understand why the government wants to state its support for what it views as a false equality.
As both have repeatedly made clear, they cannot see how the marriage of man and man or woman and woman could ever have the same sacred parity as the marriage of a man and a woman.
The Rev Sharon Ferguson, a pastor of the Metropolitan Community church, prefaced her reaction to Wednesday's announcement with the phrase, "Without wanting to sound incredibly pessimistic …"
Almost two years ago, Ferguson and her partner, Franka Strietzel, applied for a marriage licence at Greenwich register office and were refused because the law defines marriage as between one man and one woman.
After asking for a letter confirming the refusal, they – with three other gay couples and four straight couples who were applying for civil partnerships – put in an application to the European court of human rights claiming the legislation violated their human rights.
"Equality is about everybody having the same choices: what we should be having is a situation where gay couples have the choice to opt for a civil partnership, a civil marriage or a religious marriage, and that straight couples have exactly the same thing too."
"There should not be any difference, and to be quite honest, the majority of society don't understand why we have this strange system of civil partnerships and why we don't just have marriage for everybody."
The lesbian, gay and bisexual charity Stonewall was more upbeat, declaring declared itself delighted that the consultation was "finally taking place".
Its chief executive, Ben Summerskill, called on the government to speed up legislative changes, saying: "The steps necessary to extend the legal form of marriage to same-sex couples needn't take much parliamentary time. We look forward to this important measure being included in the Queen's speech on 9 May and being enacted as soon as possible."
More guarded was Peter Tatchell, veteran human rights campaigner and co-ordinator of the Equal Love campaign, which wants to see the bans on same-sex civil marriages and opposite-sex civil partnerships overturned.
"We are unhappy that the government intends to maintain the ban on heterosexual civil partnerships and the ban on religious same-sex marriages, even if faith organisations wish to conduct them," he said. "This is not equality. It perpetuates discrimination."
While he described the government's decision to hold a consultation as a heartening "and very surprising" –turn of events, Tatchell said he did not expect faith groups to agree. "I fear that religious leaders will mount a vicious, scaremongering campaign against these proposals," he said. "But we know that most of the public – including most Christians – support gay equality."
A spokeswoman for the Roman Catholic church in England and Wales said the church had nothing to add to the letter – written by the archbishop of Westminster, Vincent Nichols, and Peter Smith, the archbishop of Southwark – which was read out during mass in 2,500 churches last weekend.
In it, the archbishops said Catholics had a "duty to do all we can to ensure that the true meaning of marriage is not lost for future generations".
Changing the legal definition of marriage, they added, would be a "profoundly radical step", which would strip the union of its "distinctive nature".
The Church of England released a statement reiterating its commitment "to the traditional understanding of the institution of marriage as being between one man and one woman".
The church supported the rights that civil partnerships conferred on same-sex couples, but "opening marriage to same-sex couples would confer few if any new legal rights on the part of those already in a civil partnership, yet would require multiple changes to law, with the definition of marriage having to change for everyone".
The Coalition for Marriage – an umbrella group opposing moves to redefine traditional marriage – took a full-page advertisement in Thursday's Daily Telegraph accusing politicians of "meddling with one of our greatest national institutions" and urged people to sign a petition to keep the law unchanged.
The coalition's campaign director, Colin Hart, dismissed the consultation as "a sham" and said the government was ignoring the public.
"Not only are they redefining the meaning of marriage, they're redefining the meaning of consultation," he said. "None of the main political parties proposed redefining marriage in their manifestos and the impact assessment misses out many of the possible problems that could occur if this institution is redefined, for example how this change will affect our schools."
The institution of marriage was not the "plaything of the state" and could not be redefined by "a few politicians obsessed with appearing 'trendy' and 'progressive'".
As far asFerguson is concerned, however, her belief in the need for same-sex marriage has nothing to do with fashion or right-on thinking and everything to do with the more enduring virtues of love and faith.
"For someone who's religious, marriage is a sacrament, and a sacrament is an outward sign of an inward grace," she said.
"But the point of having a religious marriage is that we are then fulfilling that sacrament; we are doing that outward sign to celebrate the grace and love that God had given us for each other. This is incredibly important for me. This is something absolutely missing in a civil partnership or in a civil marriage. They are just legal contracts."