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In a previous post I discussed a framework for how to understand the concept of authority within God’s plan for marriage. In this post I’d like to dig down deeper into God’s design to consider something even more foundational for marriage. After all, the distinct roles assigned to husband and wife within a marriage should be carried out, well, within a marriage. The fundamental essence of marriage is captured by this biblical phrase: two become one flesh. The head-with-helper, love-and-submit complementarity of a husband and wife flourishes particularly within this foundational reality.

Two Become One

“One flesh” is the two-word summary for God’s design for marriage. These two simple words describe the most beautiful and demanding human relationship imaginable.

After joining Adam and Eve together in holy matrimony, God declared this design normative for all future marriages (Gen. 2:24). Jesus reaffirmed this design (Mt. 19:5-6), as did his apostles (Eph. 5:31, 1 Cor. 6:16). What does it mean? On a very surfacy level, becoming “one flesh” simply means the bride and groom start a new family unit with each other. Two people from totally different families become each other’s closest kin. But labeling the relationship “one flesh” goes much deeper than that.

Nothing has been more helpful for me on the meaning of this phrase than a powerful little book by Ray Ortlund called Marriage and the Mystery of the Gospel. I don’t know how I could serve you better than to simply quote him at length:

“‘One flesh’ is the biblical definition of marriage in two brief but freighted words. This expression names marriage as one mortal life fully shared. The word one bespeaks a life fully shared, and the word flesh suggests the transient mortality of this life (Gen. 6:3; Ps. 78:39). So in the one-flesh union of marriage, all the boundaries between a man and a woman fall away, and the married couple comes together completely, as long as they both shall live. In real terms, two selfish me’s start learning to think like one unified us, building a new life together with one total everything: one story, one purpose, one reputation, one bed, one suffering, one budget, one family, and so forth. Marriage removes all barriers and replaces them with a comprehensive oneness. It is this all-encompassing unity that sets marriage apart as marriage, more important than even the most intense friendship… Friends have much in common, but wise friends also have boundaries. They do not share everything. And there is much good in friendship, limited as it is. But what distinguishes marriage is the all-inclusive scope of its claims upon both the man and the woman. The two become ‘one flesh’ – one mortal life fully shared – with total openness, total access, total solidarity, for the rest of their earthly days…

In the demandingly all-encompassing context of biblical marriage we also find our greatest earthly comfort: ‘And the man and his wife were both naked and were not ashamed’ (Gen. 2:25)… [they] are naked, face-to-face in a relationship of complete belonging and total vulnerability, where they experience full acceptance with no shaming. Even so, a biblical marriage today offers the comfort of being known intimately by another and not embarrassed or ridiculed for any reason, but only welcomed and put at ease and embraced.”¹

All that a husband is, and does, and has, should be freely given for his wife, and rightfully belongs to her. All that a wife is, and does, and has, should be freely given for her husband, and rightfully belongs to him. To be one flesh means neither one builds a fence around part of his or her life and then tells the other, “You can’t come in here. I’m not going to share this part of my life, or this part of myself, with you.”² Likewise, there should be no part of the other’s life about which one says, “Stay away. I do not welcome and receive this part of you.”

In the Bible’s Song of Songs, married lovers exclaim the joy they find in completely belonging to each other: “My beloved is mine, and I am his” (2:16). Again, “I am my beloved’s, and my beloved is mine.” (6:3). These are exclamations of glad and total self-giving. I am hers. She is mine. You can’t get more comprehensive than that. You could not give to another more than that. This is one mortal life fully shared.

Imagine how much this one-flesh vision of marriage might helpfully serve as a foundation for all of the specific marriage “issues” (e.g. husband and wife roles, sexual intimacy, child rearing, etc.) that come up so often in our counseling ministries. I believe we will counsel people more effectively the more we learn to view (and teach) various marriage “topics” against the backdrop of this one-flesh blueprint.

This Mystery Is Profound

Moreover, when we wrap our minds around what God intends for the one-flesh relationship of marriage, we’re also equipped to understand the beauty of the gospel more deeply. It isn’t only marital headship and submission that displays the glory of Christ’s relationship with his people. “Two becoming one flesh” is part of the profound marriage mystery that refers to Christ and the church (Eph. 3:31-32; cf. 1 Cor. 6:16-17).

In the gospel, Jesus takes our sin and pays for it as if our debt was his. Then he gives us a share in his righteousness, his Spirit, his holy character, his resurrection, his status as a beloved son of the Father, his inheritance, his kingdom, and even his reign/enthronement. John Calvin exults in this one-flesh gospel: “We hear our Lord Jesus Christ call us to himself and tell us that we are so joined to him that he does not have anything of his own which he does not share with us and of which he will not have us as partakers.”3

This is why the apostle Paul can make astounding claims to Christians like this one: “all things are yours.” All things? Really? He expands on the statement: “whether Paul or Apollos or Cephas or the world or life or death or the present or the future—all are yours.” How can that be? The answer follows: “you are Christ’s” (1 Cor. 3:21-23).

The highest blessing, though, that the church receives from her one-flesh relationship with Christ is none other than Christ himself. Our Lord Jesus does not merely take all our debts and give us all his blessings in some abstract and impersonal manner. Ultimately, he gives us himself to know and love, in total self-giving. Christ also loves and receives all his people, calling us to give up ourselves totally to him.

Thus, understanding God’s plan for marriage – total oneness – does even more than helpfully color the ways we think about and relate to our spouses. The payoff for understanding this design is even higher: it helps us see the light of the glory of the gospel shining more brightly.


 1. Ray Ortlund, Marriage and the Mystery of the Gospel (Wheaton, IL: Crossway, 2016), pp. 30-32. Used by permission of Crossway, a publishing ministry of Good News Publishers, Wheaton, IL 60187, www.crossway.org. Emphasis original.

One finds similar explications of Genesis 2:24 in contemporary biblical counseling literature. E.g. Wayne Mack: “God’s blueprint for marriage involves one flesh. At its most elementary level, this is referring to sexual relations or physical union… But becoming one flesh involves more than the marriage act. Indeed, the marriage act is the symbol or culmination of a more complete oneness, of a total giving of yourself to another person… One definition of marriage that I really like is: Marriage is a total commitment and a total sharing of the total person with another person until death. God’s intention is that when two people get married they should share everything – their bodies, their possessions, their insights, their ideas, their abilities, their problems, their successes, their sufferings, their failures, etc. A husband and wife are a team and whatever each of them does must be done for the sake of the other person, or at least it must not be to the detriment of the other person. Each must be as concerned about the other person’s needs as he is about his own (Eph. 5:28; Prov. 31:12, 27)… This one flesh concept must manifest itself in practical, tangible, demonstrable ways. God does not intend it to be merely an abstract concept or idealistic theory, but a concrete reality. Total intimacy and deep unity are part of God’s blueprint for a good marriage… And just as sin entered and hindered the oneness of Adam and Eve, so our sinfulness is still the great barrier to marital oneness today.” Mack, Strengthening Your Marriage (Phillipsburg, NJ: P&R, 1999), pp. 6-8. Emphasis original.

2. This illustration is adapted from Ray Ortlund’s exposition of Eph. 5:22-33. See Ortlund, Marriage and the Mystery of the Gospel, p. 95.

3. Quote drawn from Ortlund, Marriage and the Mystery of the Gospel, p. 99. Ortlund cites Calvin, Sermons on the Epistle to the Ephesians (Edinburgh: Banner of Truth, 1975), p. 616.


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