The theme of union with Christ occurs in numerous places in the New Testament, and is also pictured in the Old Testament.^^ It is that union enjoyed by believers, individually and corporately, with the Lord Jesus. It is sometimes referred to as the unio mystica or mystic union, as its fact is established without understanding the mechanism. Our union with Christ is best understood by the picture-language used in the Bible, and by the blessings we derive from our union with Christ.
The language of union with Christ
Jesus (in John's gospel), John and Paul all talked about union with Christ, each using different language to point to the one reality. There are also Old Testament and New Testament pictures of union which point forward to the antitype.
Old Testament pictures
The most prevalent picture of union with Christ is that of being clothed in another. Adam and Eve, naked and ashamed in the Garden, are clothed with garments of skin (Gen. 3:21) and Jacob appears before his father in skins to appear as though his brother, Esau. Adam and Eve's shame is covered through the death of another, and Jacob only acquires blessing in his elder brother.
The Psalms also hint at union with God when they talk of finding the LORD to be a fortress and a refuge (e.g. Ps. 18:2), while the later Prophets frequently use the imagery of a husband and a wife to describe the relationship between God and Israel, an image picked up in the New Testament.
In John's gospel, Jesus describes himself as the Vine, and the disciples as branches in him (John 15:1–17). This is an extended metaphor, in which the Father is the gardener, and Jesus describes how unfruitful branches will be cut off, and that the only way to bear fruit is to remain in the vine. Branches which wither or are cut off are thrown in to the fire and burned, but the chosen branches will bear fruit which will last. Jesus goes on to say that his disciples do not belong to the world, but (by implication) they belong to him.
In his first epistle, John picks up much of that language, writing "Those who obey his commands live in him, and he in them. And this is how we know that he lives in us: We know it by the Spirit he gave us." Union with Christ means more than simply drawing one's life from Christ; it means living in him. Further, through our union with Christ, we enjoy union with the Father, since by seeing "that what you have heard from the beginning remains in you … you also will remain in the Son and in the Father." (1 John 2:24)
In the Book of Revelation, John "heard what sounded like a great multitude … shouting: 'Hallelujah! … the wedding of the Lamb has come, and his bride has made herself ready. Fine linen, bright and clean, was given her to wear.' (Fine linen stands for the righteous acts of the saints.)" (Rev. 19:6–8) Once again, this picks up on previous language, but here it is the Old Testament picture of being clothed with another which is brought through.
It is Paul's epistles that the fullest treatment of the theme of union with Christ is to be found. That union is the bedrock of the logic in Romans and the wellspring of praise in Ephesians. In Ephesians 2:20–21, Paul uses the picture of building the Church "on the foundation of the apostles and prophets, with Christ Jesus himself as the chief cornerstone. In him the whole building is joined together and rises to become a holy temple in the Lord." A similar picture can be found in 1 Corinthians 3:10–11, where this time, Paul describes Jesus himself as the foundation of the building, which seems to be the Church, described a few verses later as God's temple.
In Ephesians 5:30–32, Paul describes the relationship of Christ and the Church as being like that between a husband and wife. He also likens the Church to a body, of which Christ is the Head. This picture is developed in much more detail by Paul in 1 Corinthians 12:12–27, with particular respect to the importance of unity.
Another aspect of union with Christ is that of "Christ in us". Paul uses such language in Galatians, where he writes "I have been crucified with Christ and I no longer live, but Christ lives in me. The life I live in the body, I live by faith in the Son of God, who loved me and gave himself for me." (Gal. 2:20) To the Colossians, Paul writes that "God has chosen to make known among the Gentiles the glorious riches of this mystery, which is Christ in you, the hope of glory." (Col. 1:27)
The pictures taken as a whole, and considering other biblical language, allow us to see that there are two components to union with Christ: we in Christ, and Christ in us. It is a bond secured through faith (Gal. 3:20, Eph. 3:17) and sealed in baptism (Rom. 6:3–4, Gal. 3:26–27), and, as Ephesians 1:3–14 tells us, is a Trinitarian bond:
- the Father is the source of our union;
- the Son is the object of our union; and
- the Spirit is the bond of our union. 
The chief blessing of union with Christ is the blessing of the promises of God, for it is in Christ that all God's promises are "yea" and "amen", and when found in him, we become partakers of those promises (Eph. 3:6). We may well say, then, that it is on account of Christ that we enjoy all the good things God so richly bestows. We shall divide the blessings under three heads: blessings for believers with respect to God, with respect to one another and with respect to themselves.
Blessings to believers towards God
Grudem does well to observe that
… every aspect of God's relationship to believers is in some way connected to our relationship with Christ. From God's counsels in eternity past before the world was created, to our fellowship with God in heaven in eternity future, and including every aspect of our relationship with God in this life—all has occurred in union with Christ. (p. 840)
Paul begins his meditation on union with Christ in Ephesians 1 with a shout of "praise be to the God and Father of our Lord Jesus Christ, who has blessed us in the heavenly realms with every spiritual blessing in Christ!" In what follows, he explicitly grounds election (4), adoption (5), grace (6) and redemption (7) "in Christ", culminating in the first peak, looking towards the time when God will "bring all things in heaven and on earth together under one head, even Christ." He then begins again with election in Christ (11), reminding the Ephesians that they, too, "were included in Christ when [they] heard the word of truth, the gospel of [their] salvation." (13)
In Romans 6–7, Paul expounds union with Christ with respect to sin and the Law, showing us that we are dead to sin but alive to God in Christ Jesus. His argument is that, since we died (in Christ) to the Law, we died also to sin (since where there is no Law, there is no sin), and are now under grace. We have also been raised to new life in Christ's resurrection, and will, one day, be renewed in our bodies, in the power of Christ's resurrection. This is part of the hope of glory mentioned by Paul in his letter to the Colossians.
Imputation, of our sin to Christ, and his righteousness to us, also occur in union with Christ: hiding in him, the punishment for our sin falls on him; clothed in him, the righteousness of his life becomes our own.
Blessings to believers towards others
The main theme of union with Christ as it affects our relationships is to promote unity in the Church: being united vertically with Christ, we are naturally united horizontally with each other. In 1 Corinthians 12, Paul describes the different talents and gifts as being analogous to different parts of the body: eyes, hands, feet etc. Therefore, we should seek to build each other up in our respective gifts.
In Galatians 3:28, Paul's argument is that, since all are one in Christ Jesus, there is then "neither Jew nor Gentile, slave nor free, male nor female"— there is no place for discrimination on the basis of the status into which someone was born, as all are born again into the same status in Christ.
Blessings to believers towards themselves
When found in the Vine, branches enjoy growth and produce fruit. Believers can be assured that, on the basis of their union with Christ, they will experience a long-term pattern of growth, as Christ in them conforms them to his likeness. Discipline is another of the blessings of union with Christ, as we are pruned by the Father so as to bear fruit. We also enjoy protection when found in Christ, who makes himself our shield and stronghold. Paul's wonderful description of the armour of God is truly the armour of Christ, as each piece he describes is to be found only in union with Jesus, who alone is truth and righteousness.
Finally, "our hearts are restless, until they find their rest in thee" (attrib. St. Augustine). It is only in Christ that we find our true identity, for he is the true Man.Relevant passages
- Romans 6:1-23
- Galatians 2:20
- Ephesians 1:3-14
- Ephesians 5:22-33
- ↑ Unless otherwise noted, all Scripture quotations in this article are taken from the New International Version.
- Bird, Michael F. "Incorporated Righteousness: A Response to Recent Evangelical Discussion Concerning the Imputation of Christ's Righteousness in Justification" Journal of the Evangelical Theological Society, Vol. 47, No. 2 (June 2004): 253–275.
- Grudem, W, Systematic Theology. Zondervan, 1994. ISBN 0851106528
- Murray, J, Redemption Accomplished and Applied. ISBN 0802811434
- Torrey's Topical Textbook
- Calvin's Doctrine of our Union with Christ, Seng-Kong Tan
- Mystic Union between Christ and the Saints, by Thomas Watson
- Mystical Union Between Christ and the Saints (Monergism.com)
- Notes on Richard Gaffin's lecture on Union With Christ, by Tony Reinke
- Bibliography of Resources on Union with Christ, by Phil Gons
- An Annotated Bibliography of Resources Pertaining to "Christ in You" and "Union with Christ", by James A. Fowler