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Sex and the Mystery of Marriage

Last week I shared three articles titled A Picture-Perfect Marriage. That short series looked to Ephesians 5 and the great mystery that is marriage. I showed from that text that marriage is, and always has been, a portrait of Christ and his church. But at the end of it all I was left with a question: What is the role of the sexual relationship in this great mystery? I had to take a shot at answering that question at a recent conference and want to share today how I understand it.

We have established that marriage is a portrait of Christ and the church and that both husband and wife have a part to play in this portrait. The wife completes her part when she joyfully submits to the leadership of her husband and the husband completes his part when he joyfully and lovingly gives himself up for his wife. But how does the sexual relationship fit into God’s good design for marriage? I will admit from the outset that the answer isn’t quite as clear in Scripture as I might have expected, but I will give it a try and eagerly await your feedback.

God’s Good Design

It ought to go without saying that the Bible knows no good in sex outside of the marriage relationship. In love God says that within marriage sex is to be enjoyed and to be enjoyed freely and regularly; in love God says that outside marriage, sex of any kind is strictly forbidden. Why? Because God designed sex for a specific purpose and that purpose can only be expressed within marriage. Any other expression of sexuality, whether that is adultery or fornication or any kind of self-centered sex—all of these things ignore God’s design for sex and reinterprets it according to our sinful designs.

To understand why God says that sex is to exist only within marriage, we need to look at the covenantal nature of the marriage relationship. Marriage is a covenant that a husband and wife enter into, a covenant in which they come together before God and before other people and are made one. It is not the rings or the white dress or even the sexual union that makes marriage, but the covenant (which is why, in older times, betrothal was considered as unbreakable as marriage). While husband and wife obviously remain two individuals, two independent life forms, there is now a sense in which God regards them as one entity. Each is now responsible to the other and joined to the other to such an extent that in some mysterious way God now views them as being one. In Ephesians 5 Paul goes all the way back to Genesis 2 and reminds the reader that “a man shall leave his mother and father and be joined to his wife and the two shall be one flesh.”

One Flesh

Now Paul was obviously aware that this talk of “one flesh” can be taken literally and is meant to be taken literally. But he goes further and shows that the bond of marriage is more than a physical joining; there is more to marriage and more to the union of husband and wife than sex.

I understand this to mean that it is in the marriage covenant that a husband and wife are joined together as one. The physical sex act is a sign of the union, the consummation of the union, and something that points to what the two have become when joined together in covenant before God and before men. It is the physical component that points to the much greater and much deeper joining.

The Marriage Sacrament

I find it helpful to think of sex as something like a sacrament within marriage (Metaphorically, of course; I use Lord’s Supper as something we are familiar with in order to explain something we may be a little less familiar with). Whatever the sexual relationship is, it is more than the mere joining of flesh. Whatever the Lord’s supper is, it is more than just the eating and drinking of a tiny little piece of bread and a tiny little sip of wine. In both cases, they are more than the sum of their parts, more than they look from the outside.

In the Lord’s Supper we take bread and wine to proclaim that we have been saved by Christ, to proclaim that we are in Christ and to receive his blessing. It is what we call an “ordinary means of grace” through which Christ truly does feed us in some mysterious way. As we participate in the Lord’s Supper we declare, “I am yours. I am yours alone. And I will be found in you at that last day.” The physical component of the Lord’s Supper is a tangible symbol of a much deeper spiritual reality.

In the sexual relationship we proclaim with our spouse that we truly are one and we declare our ongoing love and allegiance to one another. We affirm that we have given ourselves to one another in a whole and complete way. Sex proclaims, “I am yours. I am yours alone. I am committed to you to the end.” It is an ordinary means of grace to marriage through which we truly do strengthen our marriage and our bonds of love.

It is here in the marriage bed that the physical, emotional, the sexual and the spiritual meet in an unparalleled way. It is here that we allow our spouse to see us in the deepest and most vulnerable context. No one else is ever meant to see us here, to see us in this way. This is where we lay ourselves bare, where we are naked and unashamed in all that we are. This is where we abandon pretence and self-love in favor of authenticity and service. This is where we express the kind of commitment to one another that says, “We are working on this portrait together, and by God’s grace we will work on it to the end.”

If I am an unbeliever and take the bread and wine, I am declaring that things are true of me that are not true–that I am a Christian, that I belong to Christ, that I am part of the family of Christians participating in Lord’s Supper with me. I declare that I am proclaiming my joyful confidence in the Lord’s return. And yet if I am not a Christian, all of this is a lie. I am making a mockery of this means of grace and calling down God’s judgment on myself.

In the same way, if I have sex with someone who is not my spouse, I am declaring that I am one with her, that I am committed to her to the end, that I am willing to give up my life for her. And yet because I have not covenanted with her in marriage, I am not truly one with her and am making a mockery of God’s good design for sex. In the same way, I am calling down God’s judgment on myself.


That, then, is how I understand sex within marriage. It is the physical component and a physical reminder–celebration, even–of a much deeper kind of joining. It is a vital part of God’s good design for marriage, which is, in turn, a vital part of God’s good design in calling a people to himself.

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