‘It’s all just semantics.’ I’ve often heard a disagreement fall to ground when one side utters this withering statement. Nobody likes being the guy who is arguing over the meaning of a word.

But in the case of so-called ‘gay marriage’ words really do matter.

As we stand, things are up in the air as to whether there will be a change in the law. The House of Commons voted in favour, and the marriage bill will go on to the next debating chamber. Supposing it goes through, and in due course gay people are lining up to become legally ‘married’, what happens next?

I want to suggest that Christians have missed something here. Regardless of what is or is not the law, there is a more fundamental issue at stake and that has to do with how we think about marriage, and then how we speak about marriage. Most of us who love God’s word are clear that the idea of marriage is not ambiguous. It is a life-long covenantal relationship between a man and woman, with the potential for procreation. It is also a powerful reflection of the relationship between Christ (the husband) and his bride (the Church). Marriage matters enormously for many reasons, but this analogy between earthly marriage and Jesus marrying his bride is one of the most important reasons God gave us marriage in the first place. It wasn’t the case that God invented marriage, and then later realised he’d come up with a brilliant picture to describe Jesus’ love for us. It was rather the case that God predestined Jesus to be wedded to his bride, and then gave us marriage as a way of understanding that relationship. There’s a lot more that could be said on the subject, but right now we just need to agree on this point: marriage matters to God, and he alone defines what marriage is.

Along comes David Cameron and suddenly marriage is now said to be something two men, or two women, can enjoy. What is going on here?

Essentially, though this is framed as a battle over the law, with an aim to create ‘equality’ for all, the real issue is that this is a battle over words. If the public can change its mind and think of committed gay relationships in the same way that we think of the covenant of marriage, then a huge battle has been won at the ideological level.

And that is why I am suggesting that for us Christians, who are watching this tragedy unfold, we had better realise that the real issue is not what the British parliament says about marriage. The real issue is what we believe about marriage. When we start talking about ‘gay marriage’ we have already lost the war, to a certain extent. Why? Because there is no such thing as ‘gay marriage’ (any more than ‘time travel’ or ‘square circles’). It is a nonsensical use of words. Marriage, by definition, is a covenant relationship between a man and a woman; I say by definition because God defined it. The cutting of the covenant takes place on the wedding day through the utterance of vows (something gay people can do) and then the consummation on the wedding night (something gay people cannot do).

Consummation with sex is a vital part of this covenant. The Hebrews spoke of ‘cutting covenants’ and often blood was involved. One example, of course, is circumcision. When the foreskin is removed an act of cutting the covenant has taken place; the boy belongs to the covenant people. And sex is like that. It is an act which, when done for the first time, may draw blood as the hymen is torn. It is the joining of souls, becoming one flesh. It involves very specific parts of the anatomy, and may result in the conception of life. So vows and (real) sex go together, in God’s order, to seal a life-long covenant relationship in the sight of God.

Gay people cannot marry one another. And regardless of what the government says on this issue, I would suggest that Christians get that clear in their heads, and also in the way we speak. By naming it ‘gay marriage’ we’re already conceding ground and speaking nonsense.