Union with Christ is one of the central doctrines of the Christian faith. The vital union that believers have with Jesus Christ makes them recipients of all the spiritual blessings that are found in Him as the Mediator and Redeemer of the elect. There are eternal and temporal aspects to this union that are distinguished in the Scriptures. The New Testament Epistles allude to union with Christ in some manner of speaking more than two hundred times. The Holy Spirit unites believers to Christ by working faith in them. Union with Christ is the source of a believer’s communion with God and other believers—since all believers are united to one another by virtue of their union with Christ. Believers remain united to Christ throughout their entirety of their lives and for all eternity. In recent decades, union with Christ has become a matter of debate inasmuch as it is bound up with central arguments in the teaching of certain proponents of the New Perspective(s) on Paul.
Union with Christ is central and essential to the Christian faith. Unless sinners are united to Jesus, they remain unable to receive any spiritual blessing from God, since “every spiritual blessing in the heavenly places” is bound up “in Christ” (Eph. 1:3). By union with Christ, God confers on the elect all the saving benefits Christ merited by His life, death, and resurrection. Union with Christ occurs in the application of redemption.
The New Testament refers to union with Christ with a variety of phrases. In the Pauline Epistles, the phrases “in Christ” (en Christo), “in the Lord” (en kyrio), “in Christ Jesus” (en Christo Iēsou), and “in Him” (en auto) appear more than two hundred times. This is Paul’s favorite designation for the spiritual identity of believers. Speaking of himself in the third person, while explaining the privilege of God’s grace and calling toward him, Paul said, “I know a man in Christ” (1 Cor. 12:2). When he explains what had happened to him when he was redeemed, he says: “I have been crucified with Christ. It is no longer I who live, but Christ who lives in me. And the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me” (Gal. 2:20–21). This is the language of vital union with Christ.
The Scriptures teach a threefold union with Christ: an eternal (i.e., decretal) union, a redemptive-historical union, and an existential union. Paul alludes to the eternal aspect of union with Christ in Ephesian 1:4, where he writes, “The God and Father of our Lord Jesus Christ . . . chose us in him before the foundation of the world.”
Paul recognizes the redemptive-historical dimension of union with Christ in Romans 6:5–11. Everything that Jesus did during His earthly ministry, He did as the representative of those chosen in Him before the foundation of the world. This means that when Jesus died, the old nature of the elect was crucified with Him (Gal. 5:24). Union with Christ makes the imputation of sin and righteousness possible. Because believers are united with Christ in the eternal election, their sins could be imputed to Him in the redemptive-historical union. In this way, Christ truly atoned for the sins of God’s people, as their sins were placed on Him. In turn, the righteousness of Christ clothes believers because He perfectly represented those with whom He was united eternally (2 Cor. 5:21).
The Holy Spirit unites believers to Christ. The Holy Spirit, by whom Christ offered Himself without spot to God (Heb. 9:14), regenerates the elect when He unites them to Christ. By this vital spiritual union, God brings the elect from spiritual death to spiritual life (Rom. 5:6). This is the existential aspect of union with Christ. Before this act, believers remain outside Christ and are “dead and sins and trespasses” like the rest of fallen humanity (Eph. 2:1–4).
The Holy Spirit does not simply unite individuals to Christ, He unites the entire invisible church (all those who profess faith and actually possess faith) to Him. In Christ, God brings together believing Jews and gentiles in one body. Every believer becomes a true descendant of Abraham by virtue of this union. Scripture calls the new covenant church the “body” and “bride” of Christ on account of this union. Herman Bavinck explained the nature of the union that exists between Christ and the church: “The union between Christ and the church is as close as that between the vine and the branches, between bridegroom and bride, husband and wife, cornerstone and building. Together with him it can be called the one Christ (1 Cor. 12:12). It is to perfect the church that he is exalted to the Father’s right hand. Just as through his suffering and death Christ was exalted in his resurrection and ascension to be head of the church, so now the church has to be formed into the body of Christ.”
The result of this union between Christ and His church is that the individual members of His body are united to one another and have a mutual communion and fellowship with the triune God and all other believers. The Westminster Confession of Faith explains this as follows: “All saints, that are united to Jesus Christ their Head by His Spirit and by faith, have fellowship with Him in His grace, sufferings, death, resurrection, and glory: and, being united to one another in love, they have communion in each other’s gifts and graces, and are obliged to the performance of such duties, public and private, as do conduce to their mutual good, both in the inward and outward man.” This communion is strengthened by a continual use of the means of grace—especially in the Lord’s Supper as believers jointly feed on Christ by faith.
Even in death, believers remain united to Christ. The Westminster Confession notes that even the bodies of believers in the grave remain united to Christ. This is what secures their bodily resurrection and glorification on the last day. In the state of glory, believers will be forever united to Jesus in everlasting holiness and perfection.
In recent years, certain proponents of the New Perspective(s) on Paul have appealed to union with Christ in an effort to minimize the importance of the ordo salutis (i.e., the order of the application of salvation) and to conflate justification and sanctification for a final standing before God. In response, we should not set aside a true understanding of union with Christ. Rather than setting aside the distinct spiritual blessings of redemption, union with Christ makes it possible for believers to experience the distinct but inseparable benefits of regeneration, justification, sanctification, adoption, and glorification (1 Cor. 1:30). Union with Christ allows the benefits of redemption to remain distinct from one another, while keeping the believer’s focus on Jesus Christ as the source of blessing.
The believer’s union with Christ has long been a neglected doctrine in many churches, yet it is a central doctrine in Scripture. God’s Word teaches us that we are chosen in Christ before the foundation of the world and that we are united to Christ by God’s justifying grace alone through our faith alone because of the atoning death of Christ alone (John 15:4–7; 1 Cor. 15:22; 2 Cor. 12:2; Gal. 3:28; Eph. 1:4; 2:10; Phil. 3:9; 1 Thess. 4:16; 1 John 4:13). The nature of this union is not only that we are in Christ but that He is in us (John 6:56; Rom. 8:10; 2 Cor. 13:5; Gal. 2:20; Eph. 3:17; Col. 1:27). The theological implications of our union with Christ are astounding, and it is Christ Jesus Himself who taught us what they are. In John 15, Jesus said: ‘I am the vine; you are the branches. Whoever abides in me and I in him, he it is that bears much fruit, for apart from me you can do nothing’ (v. 5). At the root of our sanctification is our union with Christ. As branches, we bear fruit precisely because we are united to Christ the vine, and we are connected to the vine because of the work of God the Father, who is ‘the vinedresser’ (15:1).
There are a number of passages throughout the Scriptures that reveal believers are joined to Christ: We are the branches and Jesus is the vine (John 15:5); Jesus is the head and we are His body (1 Cor. 6:15–19); Christ is the foundation and we are living stones joined to the foundation (1 Peter 2:4–5); and marriage between a husband and wife ultimately points to the union between Christ and believers (Eph. 5:25–31). Beyond these biblical images, the specific phrase ‘in Christ’ occurs some twenty-five times in Paul’s epistles. We can say that union with Christ entails all of the benefits of our redemption.