When Christians think about the perfect marriage, we should not take our primary cues from romantic comedies. But we can take at least one cue: we should be able to look our spouse in the face and say, “You complete me.”

If you don’t believe me, let’s hear from John Calvin. Writing about the first marriage, he said,

Something was taken from Adam, in order that he might embrace, with greater benevolence, a part of himself. . . . He now saw himself, who had before been only half complete, rendered whole in his wife. (Commentary on Genesis 2:21)

This completeness of husband and wife is why the apostle Paul can say that to love your spouse is to love yourself (Ephesians 5:28). The two really are one, and this means so much more than sentiment. It means they are one flesh.

Living Together as One

Paul writes,

In the same way husbands should love their wives as their own bodies. He who loves his wife loves himself. For no one ever hated his own flesh, but nourishes and cherishes it, just as Christ does the church, because we are members of his body. “Therefore a man shall leave his father and mother and hold fast to his wife, and the two shall become one flesh.” This mystery is profound, and I am saying that it refers to Christ and the church. (Ephesians 5:28–32)

What does it mean to live as one? Here are some implications of the husband and wife being one flesh.

One Body

“The two really are one, and this means so much more than sentiment. It means they are one flesh.”

To understand this oneness, we have to see that it is the oneness of Genesis 2:21–24. It is the oneness of one body. God created Adam first, but Adam is incomplete: “It is not good that the man should be alone.” Even among the animals, “there was not found a helper fit for him” (Genesis 2:18, 20). So God created the suitable helper for Adam, and did so from Adam’s own body (1 Corinthians 11:8).

When Adam sees Eve, he says, “Bone of my bones and flesh of my flesh” (Genesis 2:23). And so, the Scriptures say, it is for this reason that “a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh” (Genesis 2:23–24; Ephesians 5:31). Because they are one flesh, they shall become one flesh.

One Mission

Marital oneness creates oneness of vocation. Adam was given an original calling, to be fruitful and multiply, to fill the earth and subdue it, and this is something that he was unable to do alone (Genesis 1:28; 2:18). So woman was made for man (1 Corinthians 11:9). Unlike the animals, woman alone was a suitable helper for this job (Genesis 2:20).

One Union

Biblical oneness requires leaving other unions, notably one’s parents. Psalm 45 explains this by way of joining a new household: “Hear, O daughter, and consider, and incline your ear: forget your people and your father’s house, and the king will desire your beauty” (Psalm 45:10–11). This tells us that the marital union is distinct from extended kinship communities. It begins a new head-body relationship. Thus, the conjugal family is the most basic civic institution. It is one flesh.

One Promise

A third meaning of biblical oneness is permanence. Jesus himself makes this connection: “So they are no longer two but one flesh. What therefore God has joined together, let not man separate” (Matthew 19:6). Even for Christians and churches that acknowledge certain stipulated grounds for divorce, divorce is always tragic because it rips apart a body. Like death, divorce separates two things that belong together. And so, Christians enter into marriage vowing a commitment for a lifetime, and they do everything they can to make marriage last until the end.

One Love

A final implication of marriage being a one-flesh union is the logic of the love. As Paul says in Ephesians 5:28, to love a spouse is to love yourself. When a husband loves his wife, he is loving his body, and when a wife loves her husband, she is loving her head. This is why hating one’s spouse is so tragic. It’s actually a form of self-hatred. Abusing your wife is abusing yourself. Despising your husband is despising yourself.

Challenges to Living as One

I think many, if not most, Christians would say that the biblical picture of marriage is actually attractive. It is encouraging and even inspirational. But then, why is it so hard?

“Abusing your wife is abusing yourself. Despising your husband is despising yourself.”

Sin is always the first answer. The only candidates for marriage are sinners, and they will have the added disadvantage of living around, working for, and befriending other sinners. On top of this, sinful forces and evil powers will afflict and attack them during their life. Life on earth is war (Job 7:1), and our marriages exist only on the earth.

But there are certain specific and predictable challenges to living as one. All good marriage counselors know to talk about money and extended family. They warn about the dangers of working too much or spending too much time on friends and hobbies. These are predictable dangers, and they’re very real. But each of these dangers actually comes back to the question of identity: what we think marriage is and who we think we are.

Parental Influence

Our parents’ influence certainly continues after we marry, but the biblical teaching of the oneness of marriage is clear that the parents’ authority ends when the man and woman marry. The husband and wife should continue to honor and respect their own parents and their in-laws, but they must also separate from them in appropriate ways. The extended family should not put itself between the husband and wife, nor try to play them off against one another. This sort of advice is easier to give than to apply, but it all starts with understanding the oneness of marriage. The husband and wife are their own household.

Money

Money too is affected by our mindset. It divides a marriage when one partner spends without regard for the other, and this happens because they are still thinking of “mine” and “yours.” But in reality, the money, and the things, are now “theirs” — all of it.

The fourth-century church father John Chrysostom put it this way:

Above all banish this notion from her soul, of mine and yours. If she says the word “mine,” say unto her, “What things do you call yours? For in truth I know not; I for my part have nothing of my own. How then do you speak of ‘mine,’ when all things are yours?” (Homily 20 on Ephesians)

Work

Something similar goes for work commitments. In the modern world, especially with the breakdown of clear boundaries between work time and off time, people are working longer than ever before. Thanks to their smartphones, they’re still working even while they are eating, while they are walking at the park, and while they are supposed to be sleeping. But this style of working will hollow out a marriage.

The biblical oneness of marriage means that marriage comes first. Christians should understand their “job” as an extension and application of the household’s cultural mandate, one way in which they are jointly multiplying, filling the earth, and subduing it. Practically, this means that the work of our jobs has to support the more basic work of our marriage and family. If our jobs harm our family, then they are harming our own bodies.

Friends

So too, finally, with friends. While men and women are naturally going to have their own kinds of friends, and usually friends that are quite different from one another, the boundaries need to be clear. We are never “on our own” with our friends but always part of our body. Thus, what we do with our friends, and how long we do it, should be good for our spouse as well, good for both head and body.

The Marriage We All Want

Why is this a particularly Christian understanding of marriage?

This understanding of marriage is Christian because it comes from God’s word, but even more than this, it is Christian because it bears witness to Christ. It lives out the self-sacrificial love that Christ showed the church (Ephesians 5:25–27). To marry as a Christian is to enter into a lifetime of dying to self. Spouses cannot put their own desires first. They must serve the other and learn to find their joy in the joy of their beloved. Indeed, they must understand that they will succeed and flourish only insofar as their spouse is succeeding and flourishing. They will receive glory from the glory of their other half.

“To marry as a Christian is to enter into a lifetime of dying to self.”

A Christian marriage also testifies to the communion believers have with Christ. All the blessings of Christ are now ours through our union with him (1 Corinthians 3:21–23; Ephesians 1:3). We are so closely identified with Christ that we can say, “It is no longer I who live, but Christ who lives in me” (Galatians 2:20). When the husband loves his wife as Christ loved the church, and when the wife submits to the husband as to the Lord, then they are a living icon of the whole Christ.

Ultimately, this sort of marriage points to that great marriage at the end of history, when the holy city comes down out of heaven, “prepared as a bride adorned for her husband” (Revelation 21:2). It points to the great marriage where all of us, having been washed and made without spot or wrinkle, are presented to our eternal husband in splendor.

This is the marriage, standing beyond the best earthly marriages, that we all want.