Union with Christ

…that which we have seen and heard we proclaim also to you, so that you too may have fellowship with us; and indeed our fellowship is with the Father and with his Son Jesus Christ. – 1 John 1:3

One of the most comforting doctrines for the Christian believer is the doctrine of Union with Christ. Morton Smith says that “Union with Christ, therefore, is a comprehensive category that binds all the elements of the application of redemption. Union with Christ is the central truth of all soteriology” (Morton Smith, Systematic Theology:2, 491). Yet it encompasses God’s covenant with his people. Joel Beeke and Paul Smalley teach, “By ‘covenant of grace,’ we refer to the great covenant rooted in eternity, spanning history, and consisting of the solemn promises that undergird all of God’s historical covenants and are fulfilled in the new covenant by Christ. A synonym for ‘covenantal’ is ‘federal’ (from the Latin foedus, ‘covenant’), and covenant theology is sometimes called federal theology” (Joel R. Beeke and Paul M. Smalley, Reformed Systematic Theology:2, 521).  Louis Berkhof gives us a reformed definition of union with Christ: “That intimate, vital, and spiritual union between Christ and his people, in virtue of which he is the source of their life and strength, of their blessedness and salvation” (Louis Berkhof, Systematic Theology, 379).

            Considering these ideas, one may turn to The Westminster Confession of Faith, which explicitly states the doctrine as,“All saints that are united to Jesus Christ their head, by his Spirit and by faith, have fellowship with him in his graces, sufferings, death, resurrection, and glory” (WCF 26:1) (1 John 1:3, 16; Rom. 6:5-6, 8:17; Eph. 2:5-6, 3:16-18; Phil. 3:10; 2 Tim. 2:12). And The Westminster Larger Catechism question eighty-three asks and then answers: “What is the communion in glory with Christ which the members of the invisible church have with Christ? The members of the invisible church have communicated to them in this life the firstfruits of glory with Christ, as they are members of him their head, and so in him are interested in that glory which he is fully possessed of (Eph. 2:5-6); and, as an earnest thereof, enjoy the sense of God’s love (Rom. 5:5; 2 Cor. 1:22), peace of conscience, joy in the Holy Ghost, and hope of glory (Rom. 5:1-2, 14:17; 2 Pet. 3:18); as, on the contrary, sense of God’s revenging wrath, horror of conscience, and a fearful expectation of judgment, are to the wicked the beginning of their torments which they shall endure after death (Gen. 4:13; Matt. 27:4; Mark 9:44; Rom. 2:9; Heb. 10:27)” (WLC 83). One can see that, as Smith puts this way, “Union with Christ covers the whole gambit of salvation, from the sovereign purpose and election to the consummation in glory” (Smith, 491).

            Union in Christ’s first confirmation teaches Jesus Christ as the believer’s “head.” This concept emphasizes one’s federal union with Christ, where he is the federal head and representative of all who are his and his alone. Charles Hodge puts it like this: “As such He came into the world, and all He did and suffered was as a representative, as a substitute, one acting in the place and for the benefit of others. But He was the representative of those given to Him, i.e., of those who were in Him. For it was this gift and the union consequent upon it, that gave Him his representative character, or constituted Him a federal head. He was therefore the federal head, not of the human race, but of those given to Him by the Father. And, therefore, his work, so far as its main design is concerned, was for them alone” (Charles Hodge, Systematic Theology:2, 551). Therefore, Christians receive great comfort that they are graced in a relationship with the Holy God because of their union with Christ.

            The union with Christ’s second attestation inculcates the believer’s union with Christ occurs due to “the Holy Spirit’s work and the believer’s faith.” Doug Kelley explains, “Union with Christ (which brings us into his knowledge of the Father) comes about with regeneration” (Douglas F. Kelly, Systematic Theology:2, 40). That regeneration is the work of the Holy Spirit in the believer’s heart. “The Spirit of Christ baptizes them into union with Christ in his death and resurrection (Rom. 6:3-6), which provides for them the continuing power for their dying to sin and rising to new, Christ-based life (Rom. 6:6-13) (Kelly, 480 – emphasis mine). The Christian’s union with Christ empowers their sanctification to make them more into the Savior’s image.   

            However, the union with Christ is not left to the Holy Spirit alone. The believer’s responsibility puts salvation into action by faith. After Paul gives a concise chiasm of Christ’s federal work from leaving the throne of heaven to his return back upon it (Phil. 2:1-11), he then tells believers to “work out your salvation…because God is at work in you” (Phil 2:12-13). After discussing the root of the union with Christ is election, Morton Smith then quotes John Dick and R.L. Dabney: “‘The principal bond of union between Christ and his people is the Spirit. But, as the union is mutual, something necessary on their part to complete it; and this is faith.’

‘In the souls of believers, he puts forth a different agency than any and all creatures as such, viz., the same which he exerts in the Man Jesus Christ, which he fills him with all the fulness of the Godhead.’” (Smith, 493). Therefore, the believer’s faith is marked by bearing and abiding fruit (John 8:31; 15:2). It is a faith that continues to the end that involves an internal heart-change, not merely external in nature. 

            The final enlightenment espouses that the Christian’s union with Christ includes a benefit only the Christian can experience, “fellowship with him.” That fellowship then subsumes “his graces, sufferings, death, resurrection, and glory.” The Westminster Shorter Catechism question 36 includes these benefits: “…assurance of God’s love (Rom. 5:5), peace of conscience (Rom. 5:1), joy in the Holy Ghost (Rom. 14:17), increase of grace (2 Pet. 3:18), and perseverance therein to the end (Phil. 1:6; 1 Pet. 1:5)” (WSC 36). Beeke and Smalley qualify this way, “God’s faithfulness to his promise is guaranteed not only by the nature of a covenant, which even among men is inviolable (Gal. 3:15), but also by the fact that God made the covenant with his Son. God’s covenant people are adopted ‘sons,’ but Christ is the ‘Son’ (4:4-6). They received the promised inheritance because Christ is God’s rightful heir. They are covenant sons because they have ‘faith in Christ Jesus’ and ‘have put on Christ;’ in union with Christ, they are ‘Abraham’s seed, and heirs according to promise’” (3:26-29) (Beeke, 529-530). Only those who are in union with Christ can know of his peace, deal with sufferings as he did, or have joy, that is, good and righteous joy. No other creature in earthly creation can know this, nor can an unbelieving human know this kind of spiritual life. One can conclude, then, with Kelly, “In all of these blessings, the Lord has made us to share, as his Holy Spirit unites us to him who is our substitute and our representative. What a happy and loving people we are called and enabled to be!” (Kelly, 340).