Editorial: Same-sex marriage is a passport to real equality

The House of Commons will vote this evening on legalising gay marriage. But that bald statement of parliamentary timetabling masks the full import of what is happening. The Marriage (Same-Sex Couples) Bill is a historic piece of legislation that, once passed into law, will change the social landscape. It will change it for ever – no future government will be able to reverse it – and for the better. This is a modernising, reformist piece of legislation that recognises the right of everyone to be treated equally by the law, regardless of their sexual orientation.

The Bill, which will be subject to a free vote, is confidently expected to pass, and the Prime Minister, who has made much of the running on the issue since the day he was elected leader of his party, will take his MPs into the Aye lobby. But nothing like all of them. More than 100 are expected to vote against, or abstain, in one of the biggest rebellions of this parliament.

While David Cameron's position on gay marriage has been clearer, more consistent and more obviously impassioned than on almost any other issue since he was elected leader of his party – admirably so – many Conservatives disagree with him. What for Mr Cameron, for a majority in Britain, and for this newspaper, is a matter of elementary equality is seen by self-styled traditionalists in the Conservative Party as morally wrong. Opposition comes from many religious groups too, especially Roman Catholic leaders, but also the established Church in the person of the new Archbishop of Canterbury, Justin Welby – although Anglicans are divided on this, as on so much else.

Mr Cameron's neat affirmation of his position – "I don't support gay marriage despite being a Conservative. I support gay marriage because I'm a Conservative" – does not wash in these circles. Nor is it just the principle that opponents cite; they are also concerned about the practical and political implications. When more than 20 past and present constituency chairmen delivered a letter to Downing Street on Sunday, calling for any decision on gay marriage to be postponed until after the next election, their objections included their fear that Mr Cameron was jeopardising the party's hoped-for majority at the next election and their view that, at a time when there were so many other pressing issues, starting with the economy, the legalisation of gay marriage was a diversion, and a damaging one at that.

But Mr Cameron and his ministers have stuck to their guns – and their timetable – with the support of the other two main leaders, which is to their credit. The one regrettable concession that emerged only when the Bill was published – a big retreat, but not a completely fatal one – was that the Church of England would not be allowed to conduct same-sex marriages. Whatever else may have lain behind this ban, which came as an unpleasant surprise, it served to underline that the legalisation of gay marriage constitutes a reform of the civil law – no less, but no more either. That the term marriage encompasses both civil and religious ceremonies has surely been a complicating factor.

We hope, as many gay couples will do, too, that this limitation will prove temporary, and that gay weddings will be legally conducted in church, including the Church of England. But the central force of the Bill being voted on today is to give same-sex relationships the same status in law as heterosexual marriage. Where civil partnerships may be seen, with hindsight, as a progressive, if inadequate, staging post, today's vote offers the passport to full equality before the law. It is a victory that has been a long time in coming; there should be no further delay.