In his book, The Meaning of Marriage, Tim Keller quips that of Paul’s famous discourse on marriage in Ephesians 5, the one part that many couples can relate to is Eph 5:32 – marriage is a mystery! He writes, ‘sometimes you fall into bed, after a long, hard day of trying to understand each other, and you can only sigh: “This is all a profound mystery!”… an unsolvable puzzle, a maze in which you feel lost.’ [Tim Keller, The Meaning of Marriage (New York: Dutton, 2011), 21.]

And yet, with all its tremendous highs and deep lows, Paul tells us that God has established marriage for a reason. And that primary reason is not for companionship, or sex, or family, or mutual care, or the welfare of society – though marriage is about all those things. The primary purpose of marriage is to paint a picture: a picture of Christ’s incredible, self-sacrificing love for His church.

So, with all the imperfect brush strokes, when we watch a man laying down his life for his wife in loving servant leadership, and a woman willingly and lovingly submitting to such self-sacrificing leadership in her husband, we are seeing in some small measure a display of Christ’s love for His people, and of His people’s willing response to Him.

But what has all that got to do with a brothel door?

Well, when Paul writes about marriage he quotes Genesis 2:24 and says, ‘“Therefore a man shall leave his father and mother and hold fast to his wife, and the two will become one flesh.” This mystery is profound, and I am saying that it refers to Christ and the church’ (Eph 5:31-32). So, if marriage is a picture of Christ’s relationship with His church (and vice versa), the intimacy of sex within marriage – becoming one flesh - is a profound illustration of the church’s union with Christ. So not only are the self-sacrificing leadership and willing submission of husband and wife brush strokes on the canvas, so too is their physical sexual union.

Sex (between – and only between – a husband and a wife) - is a picture of the incredible, heart-rejoicing union we can enjoy with God, in Christ. But sex is only the image of the real thing. On its own it can never take the place, nor fill the heart with overflowing and inexpressible joy, like Christ can (Psalm 16:11; 1 Peter 1:8).

Augustine said that ‘our hearts are restless until they find their rest in thee, O God.’ And he was right. We can try and fill that restlessness, and satisfy it with a thousand things, but they will all fail ultimately. Even sex. It is just the image.

Which is why GK Chesterton wrote that the man who goes knocking on a brothel door, is a man looking for God. He is wanting to fill that restless void in his heart, and he thinks the ‘intimacy’ of sex will do it. But he has mistaken the image for the real thing.

Can that hunger and restless void be satisfied? Yes. But he will never find what he is looking for behind that door.

Thank God there is another door we can all go knocking on.