Union with Christ and Why It Changes Everything

You did not simply receive something from Jesus. You were joined to Him. That single truth, rightly understood, will change the way you pray, the way you suffer, the way you give, and the way you die. Yet most Christians live as though they are merely acquainted with Christ rather than united to Him. John Flavel, the seventeenth-century Puritan pastor, believed this was one of the great tragedies of the Christian life. In his sermon on John 17:23 from The Methods of Grace, Flavel set out to correct it.

Three Unions in a Single Verse

In John 17:23, Jesus prays to the Father: "I in them, and Thou in me, that they may be made perfect in one." There are three distinct unions folded into this one verse.

The first is the union between the Father and the Son. "Thou in me." The Father dwells in Christ not merely by affection, as a close friend might dwell in the heart of another, nor only by shared essence, though the Father and Son share one divine nature. The Father is in Christ as Mediator. The fullness of the Godhead dwells in Him in a way it has never dwelt, and never can dwell, in any other being.

The second union is between Christ and believers. "I in them." Christ and the Father are one essentially. Christ and believers are one mystically. The Father communicates the fullness of the Spirit to Christ as Mediator. Christ communicates the Spirit to His people in measure.

The third union follows from the second. Because the same Spirit dwells in every believer and unites each one to Christ as living members to their Head, believers are bound to one another. They are fellow members of one body. Their unity with each other is not a social arrangement. It flows from a shared connection to a living Head.

Four Pictures That Still Fall Short

How do you explain a mystery that exceeds human experience? Scripture borrows four images from the natural world to help us grasp this union. Each one reveals something true. None of them, taken alone or together, tells the whole story.

The first image is two pieces of wood joined by glue. Paul uses this language in 1 Corinthians 6:17 when he says the one who is joined to the Lord is "one spirit" with Him. The Greek word means "glued." But glue creates an intimate bond, not a living one. Our union with Christ is alive.

The second image is a graft inserted into a tree. Romans 6:5 speaks of believers being "planted together" with Christ. A graft shares the life and sap of its host. But in nature, the graft is the nobler part, and the tree takes its name from the graft. In our union with Christ, He is infinitely more excellent than we are. We are named after Him, not the other way around.

The third image is marriage. A husband and wife become one flesh, and this is a deep and tender bond. But death dissolves a marriage. Our union with Christ survives death. It cannot be broken.

The fourth image is the head and members of a body, animated by one soul. This is the fullest picture, but even here there is a deficiency. In a natural body, some members are closer to the head than others. The hand is nearer than the foot. But in Christ's mystical body, every member is equally near to the Head. The weakest believer is as close to Christ as the strongest.

Why This Union Is Real, Not Imaginary

Some would dismiss this as religious abstraction. It is not. The union between Christ and believers is not an empty notion. It is a demonstrable truth, supported by four lines of evidence.

First, communion proves union. Believers share fellowship with the Father and the Son (1 John 1:3). They are called "partakers of Christ" (Hebrews 3:14). But you cannot share in someone's benefits unless you are first connected to that person. A branch cannot draw sap from a tree it is not attached to. Remove the union, and the communion disappears.

Second, justification proves union. A believer is justified by a righteousness that is not his own (Romans 3:24). Christ's righteousness is credited to the sinner's account. But how can one person's righteousness belong to another? The answer is simple. It can, if that other person is your Head, your Husband, your Surety. You would not say Peter can be justified by Paul's righteousness. But both Peter and Paul can be justified by the righteousness of Christ, because both are members joined to one common Head.

Third, sympathy proves union. When Saul persecuted the church, Jesus said, "Why are you persecuting Me?" (Acts 9:4). Christ was in heaven. His people were on earth. Yet He felt what they felt. The head cried out when the foot was trodden upon. Such sympathy only makes sense if there is a real connection between them.

Fourth, the resurrection proves union. Believers will not be raised on the last day by the naked power of God acting from outside them. They will be raised by the Spirit of Christ dwelling within them (Romans 8:11). The vital energy that raised Jesus from the dead will flow from the Head into every member. That can only happen if the members are truly joined to the Head.

What This Union Is Not

We must also guard this doctrine from misunderstanding. There are five things this union is not.

It is not merely mental. The world may dismiss it as fantasy, but believers know its reality. Jesus Himself said, "You shall know that I am in My Father, and you in Me, and I in you" (John 14:20). This doctrine is not imaginary. It is knowable.

It is not physical, as though believers become part of Christ's literal body. Christ's human nature is united to His divine person in a unique way that belongs to Him alone. Our union with Him is mystical, not bodily.

It is not essential, as though our beings are absorbed into God's being. There is an infinite distance between us and Christ in nature and excellence, even though we are united to Him.

It is not merely federal, a union by covenant alone. A covenant relationship does exist between Christ and believers, but it rests on something deeper.

And it is not merely moral, a union of love and affection. Friends may speak of being "one soul in two bodies." Christ and believers do share deep affection. But this union binds not just our hearts but our persons to Christ.

Ten Qualities of a Union Like No Other

Having cleared away what the union is not, we can now describe what it is. Scripture reveals ten properties of this union, and each one matters for the way we live.

First, it is supernatural. No one can unite himself to Christ. "Of Him are you in Christ Jesus" (1 Corinthians 1:30). Two ligaments bind the believer to Christ: the Spirit on Christ's side and faith on ours. But even faith is not our own doing. It is the gift of God (Ephesians 2:8).

Second, it is immediate. Every member of Christ's body, the smallest and the greatest, has a direct connection to the Head. There is no hierarchy of nearness. The newest convert stands as close to Christ as the most seasoned saint.

Third, it is fundamental. Every fruit of obedience, every spiritual privilege, every hope of glory depends on this union. "Christ in you, the hope of glory" (Colossians 1:27). Destroy this union, and you destroy everything.

Fourth, it is efficacious. Divine power flows through this union to give spiritual life and to preserve it. Why does the life of grace not die under the constant assault of temptation and sin? Because the root is alive. "Because I live, you will live also" (John 14:19).

Fifth, it is indissoluble. Death dissolves marriage. Death separates soul from body. But death cannot sever the believer from Christ. "What shall separate us from the love of Christ?" Paul asked, and his answer was: nothing (Romans 8:35, 38-39). God called Himself the God of Abraham long after Abraham's body had turned to dust.

Sixth, it is honorable. The emperor Constantine valued being a member of the church above being head of the empire. Believers are not merely Christ's servants. They are His members. Angels serve Christ as noble subjects. Believers are joined to Christ as His bride. Even the greatest angels count it no dishonor to serve the heirs of salvation (Hebrews 1:14).

Seventh, it is comfortable. Whatever troubles come, the believer can say, "Christ is mine, and I am His." He is not only a Head of influence to His own people but a Head of dominion over all things, for their good (Ephesians 1:22-23).

Eighth, it is fruitful. "We are married to Christ, that we should bring forth fruit to God" (Romans 7:4). All the fruit a person produces before being united to Christ is worse than none. But Christ is a fruitful root who makes every branch in Him fruitful.

Ninth, it is enriching. By union with Christ's person, believers have a share in all His riches. His Father becomes their Father (John 20:17). His promises belong to them (2 Corinthians 1:20). His providences work for their good (Romans 8:28). His glory awaits them (John 17:24).

Tenth, and this deserves almost breathless reverence, this union means that everything Christ has becomes ours, either by communication to us or by His working on our behalf.

How Union with Christ Changes the Way You Treat Others

This doctrine cannot remain in the realm of ideas. It presses into the conscience with pointed questions about everyday life.

If believers are members of Christ's body, then serving a fellow Christian is serving Christ Himself. Jesus said, "I was hungry, and you gave Me food. I was thirsty, and you gave Me drink" (Matthew 25:35). When His followers asked when they had ever seen Him hungry, He answered, "As you did it to one of the least of these My brothers, you did it to Me" (Matthew 25:40).

A great theologian once said he doubted whether any person on earth fully understood and believed this truth. If Christians truly grasped that feeding a hungry believer was feeding Christ, how could they remain tightfisted? Christ, the Lord of heaven and earth, is sometimes in need of a penny through His suffering members. He is content to receive kindness as a gift, though He could demand it by authority.

And the reverse is also true. To harm a fellow believer is to harm Christ. "He who touches you touches the apple of My eye" (Zechariah 2:8). It would be better for a hand to wither and an arm to fall from its shoulder than for it to be raised against Christ in the person of even the poorest of His members.

Why Your Sin Wounds the One Who Gives You Life

The implication goes further still. When Satan tempts a wicked person to strike a believer, Christ is wounded by the hand of an enemy. But when Satan's temptations prevail upon a believer to sin, Christ is wounded by His own hand.

Consider how striking this image is. The eagle complained that it was wounded by an arrow feathered with its own plumage. The tree complained that it was split by a wedge cut from its own limbs. When believers sin, they wound their Head of influence, the One through whom they live. They rebel against their Head of government, the One who guides them by His counsel. They grieve their consulting Head, the One who plans and provides for their safety each day. And they dishonor their Head of honor, the One from whom all their dignity flows.

This is not a call to despair. It is a call to soberness. "If we say we have fellowship with Him, and walk in darkness, we lie" (1 John 1:6). The person who claims to abide in Christ ought to walk as Christ walked (1 John 2:6).

What Union with Christ Means When You Are Afraid

Now the doctrine turns to comfort. If Christ and believers are joined as Head and members, then believers can never truly lack what they need.

Christ knows every detail of our suffering, more fully than we ourselves know it (Psalm 38:9). He feels our afflictions as though they were His own. "We do not have a high priest who cannot be touched with the feeling of our infirmities" (Hebrews 4:15). He has more than enough to supply every need, for all things have been delivered to Him by the Father (Luke 10:22). He gives generously even to His enemies, loading them with earthly blessings. Will He then starve His own?

And He has promised that He will never leave nor forsake His people (Hebrews 13:5). That promise has never failed since the hour it was first spoken.

The logic is plain. If Christ knows my needs, feels my pain, has the resources to help, has been faithful in the past, and has pledged never to abandon me, then why is my soul troubled? There is no reason it should be.

What This Union Means at the Hour of Death

Perhaps the most tender application of this doctrine concerns death. If this mystical union cannot be dissolved by death, then believers can part with their bodies on comfortable terms.

Christ your Head is risen. Therefore you cannot be lost. He is not only risen Himself but has become "the firstfruits of those who have fallen asleep" (1 Corinthians 15:20). Believers are His members, His fullness. He cannot be complete without them. A part of Christ cannot perish in the grave.

When you feel the natural union between soul and body dissolving, remember that this mystical union can never be dissolved. The pangs of death cannot break this tie. As Paul wrote, "To me to live is Christ, and to die is gain" (Philippians 1:21).

The One Question That Remains

Flavel closed with a searching challenge. If this union is real, it must produce real effects. He urged every reader to examine whether those effects are present in their lives.

Do you see the holiness of Christ taking root in your soul? Everyone who is planted into Christ shares in the sap of sanctification. Do you love Christ above your own life? The nearer the union, the stronger the affection. Are you subject to Christ as your Head? A claim of union with Christ means nothing if your own will is still giving you law. And do you bear fruit for God? There are no barren branches growing on this fruitful root.

These are not questions designed to create anxiety. They are questions designed to bring clarity. Union with Christ is not an achievement. It is a gift. But it is a gift that changes everything it touches.

Flavel ended where all good theology ends: with worship. "O how great! how glorious a person do these little weak arms of your faith embrace!"^[1]

Short Biography of John Flavel

John Flavel (1628–1691) was an English Puritan minister whose life was marked by personal loss and persistent persecution. Educated at Oxford and ordained in 1650, he became a beloved preacher in Dartmouth before being ejected in 1662 for nonconformity. Rather than quit, he preached secretly in forests, private homes, and even on a tidal island, at times evading authorities in dramatic fashion.

Flavel married four times, losing three wives, yet continued his ministry with remarkable resilience. During periods of restricted public preaching, he channeled his gifts into writing, producing at least nine books. When religious freedom was restored under William of Orange, his congregation built him a new church.

Known for deep spirituality, fervent prayer, and heart-searching preaching, Flavel profoundly impacted many lives. He died of a stroke in 1691, his final words: "I know that it will be well with me."^[2]

Bibliography

• Beeke, Joel R., and Randall J. Pederson. Meet the Puritans: With a Guide to Modern Reprints. Grand Rapids, MI: Reformation Heritage Books, 2006.
• Flavel, John. The Whole Works of the Reverend John Flavel. Vol. 1–6. London; Edinburgh; Dublin: W. Baynes and Son; Waugh and Innes; M. Keene, 1820.