Union with Christ: The Westminster Confession
For English Reformed Orthodoxy, the doctrine of a believer’s union with Christ was paramount. John Owen, enunciating the centrality of a believer’s union, exclaimed that our union with Christ is the “principle and measure of all spiritual enjoyments and expectations.” Likewise Thomas Goodwin expressed a similar conviction that “being in Christ, and united to him, is the fundamental constitution of a Christian.” It is a bit surprising then when one looks at the Westminster Confession of Faith, that high-water mark of Puritan theological codification, where we find no chapter expressly dedicated to the doctrine of union with Christ. But this in no way means the doctrine is not there. No, it runs like a silver thread throughout the document underlying much of the theology laid out in its pages.
Perhaps the clearest place to see the doctrine is in the Shorter Catechism question 30, which asks “How doth the Spirit apply to us the redemption purchased by Christ?” The answer: “The Spirit applieth to us the redemption purchased by Christ, by working faith in us, and thereby uniting us to Christ in our effectual calling.” The language used here harkens back to Calvin’s famous passage on union with Christ in his Institutes where he asks the same question. “How do we receive those benefits which the Father bestowed on his only-begotten Son?” Calvin answers by saying we must first “understand that as long as Christ remains outside of us, and we are separated from him, all that he has suffered and done for the salvation of the human race remains useless and of no value to us.”
Calvin is getting us to see the absolute need a sinner has to be found in Christ. Indeed, this “problem” of how a sinner partakes of the benefits of salvation found in the person of Jesus Christ lies underneath the title to John Murray’s book Redemption Accomplished and Applied. We can agree that Jesus accomplished salvation in his person and at a particular point in time. The question that arises though is how that salvation is applied to sinners before or after the historical events of Christ’s life, death, and resurrection. The answer lies in the doctrine of a person’s union with Christ.
Let’s see some important ways in which the Westminster Confession and its subsequent Catechisms unpack this doctrine.
It shouldn’t surprise anyone familiar with the reformed theology of the Westminster Confession that the doctrine first arises when discussing God’s Eternal Decrees. In paragraph five we read, “Those of mankind that are predestinated unto life, God...hath chosen, in Christ, unto everlasting glory.” The Scripture referenced for this is Paul’s words in Ephesians 1:4: “He chose us in him before the foundation of the world, that we should be holy and blameless before him.” Here the focus is clearly on our being chosen in the person of Christ. This is what many Puritans referred to as our “immanent union in Christ”, a union grounded in God’s eternal election.
But this still leaves open the question of how a person actually becomes united with Christ in time. There are many elect persons who have not yet been effectually called and are therefore still, as unbelievers, under the wrath of God. Paul himself seems to get at these two senses of our union in Christ, one immanent, the other actual, when he writes, “God, who saved us and called us to a holy calling, not because of our works but because of his own purpose and grace, which he gave us in Christ Jesus before the ages began, and which now has been manifested through the appearing of our Savior Christ Jesus, who abolished death and brought life and immortality to light through the gospel” (2 Tim. 1:8-10).
Paragraph six of the Confession’s chapter on God’s Eternal Decrees begins to unpack how those who are chosen in Christ become actual partakers of Christ. “As God has appointed the elect unto glory, so has He, by the eternal and most free purpose of his will, foreordained all the means thereunto. Wherefore, they who are elected, being fallen in Adam, are redeemed by Christ, are effectually called unto faith in Christ by his Spirit working in due season, are justified, adopted, sanctified, and kept by his power, through faith, unto salvation. Neither are any other redeemed by Christ, effectually called, justified, adopted, sanctified, and saved, but the elect only.”
From here a theology of union becomes most robust in chapter eight on Christ the Mediator. And again, right from the beginning in paragraph one, we see this delineation between being found in Christ immanently, that is by election, versus being in Christ actually, that is in time and history. “It pleased God, in his eternal purpose, to choose and ordain the Lord Jesus, his only begotten Son, to be the Mediator between God and man, the Prophet, Priest, and King, the Head and Savior of his Church, the Heir of all things, and Judge of the world: unto whom he did from all eternity give a people, to be his seed, and to be by Him in time redeemed, called, justified, sanctified, and glorified.”
Crucially, it is the Divine Son’s incarnation which makes the saving of men at all possible. If men are to find salvation only in the Son, then that Son had to become a man. Indeed, as paragraph three puts it, “The Lord Jesus, in his human nature thus united to the divine, was sanctified, and anointed with the Holy Spirit, above measure, having in Him all the treasures of wisdom and knowledge; in whom it pleased the Father that all fullness should dwell; to the end that, being holy, harmless, undefiled, and full of grace and truth, he might be thoroughly furnished to execute the office of a Mediator and Surety.” In one sense then, the doctrine of our union with Christ is grounded in the more mysterious doctrine of the union of Christ’s divine and human natures!
How then do we find ourselves linked with the God-man Jesus Christ, enjoying the benefits of his saving work on the cross? Look at how chapter eleven, On Justification, accommodates a theology of union to answer this question. Paragraph four: “God did, from all eternity, decree to justify all the elect, and Christ did, in the fullness of time, die for their sins, and rise again for their justification: nevertheless, they are not justified, until the Holy Spirit does, in due time, actually apply Christ unto them.”
The answer lies in the work of the Holy Spirit effectually calling and uniting men to Christ and therein making them partakers of his life. Indeed, as paragraphs one and two of the same chapter puts it, “Those whom God effectually calls, he also freely justifies; not by infusing righteousness into them, but by pardoning their sins, and by accounting and accepting their persons as righteous; not for anything wrought in them, or done by them, but for Christ's sake alone... Faith, thus receiving and resting on Christ and his righteousness, is the alone instrument of justification.”
Here it is helpful to look at the Westminster Larger Catechism, question 70, which asks What is justification. Look at how the answer given strongly assumes union in Christ. “Justification is an act of God's free grace unto sinners, in which he pardons all their sins, accepts and accounts their persons righteous in his sight; not for anything wrought in them, or done by them, but only for the perfect obedience and full satisfaction of Christ, by God imputed to them, and received by faith alone.” The righteousness that becomes ours by imputation is a foreign righteousness. That is, it is Christ’s righteousness and it is ultimately only by being found in the Savior where we can have any participation in that righteousness!
This will of course underscore the Confession’s later stance on the Church when, again, adopting a theology of union, writes that “The catholic or universal Church, which is invisible, consists of the whole number of the elect, that have been, are, or shall be gathered into one, under Christ the Head thereof; and is the spouse, the body, the fullness of Him that fills all in all.”
All of this is none other than the hope and assurance of the Gospel as preached by Paul; the good news that we are saved and counted as righteous only because of Christ and being found in Christ! Speaking to the Corinthian church, he reminds them that because of God’s grace, “you are in Christ Jesus, who became to us wisdom from God, righteousness and sanctification and redemption” (1 Cor. 1:30). The theology of union with Christ which undergirds the Westminster Confession of Faith is a gloriously biblical theology, a doctrine which can alone give us any hope at all because it is grounded in the surety of another more righteous than us!
Stephen Unthank (MDiv, Capital Bible Seminary) serves at Greenbelt Baptist Church in Greenbelt, MD, just outside of Washington, DC. He lives in Maryland with his wife, Maricel and their two children, Ambrose and Lilou.
 John Owen, An Exposition of the Epistle to the Hebrews in The Works of John Owen (Edinburgh: Banner of Truth Trust, 1991), 20:146. I found the quote in Joel Beeke and Mark Jones, A Puritan Theology (Grand Rapids: Reformation Heritage Books, 2012), 483.
 Thomas Goodwin, Of Christ the Mediator, in The Works of Thomas Goodwin (Grand Rapids: Reformation Heritage Books, 2006) 5:350. Likewise, I found this quote in Joel Beeke and Mark Jones, A Puritan Theology (Grand Rapids: Reformation Heritage Books, 2012), 483.
 John Calvin, Institutes of the Christian Religion, ed. John T. McNeill (Louisville: The Westminster Press, 1960), 3.1.1.
 Joel Beeke and Mark Jones, A Puritan Theology (Grand Rapids: Reformation Heritage Books, 2012), 482.
 Robert Letham notes that “the doctrine of election cannot be understood biblically and theologically if it is abstracted from its being in Christ. It is a Trinitarian decree, it bears the closest connection to the person and work of Christ, it cannot be severed from the gospel, and it is the root and foundation of all the other ways in which union with Christ is worked out in human history and in the life experience of the faithful.” Letham, Union With Christ: In Scripture, History, and Theology (Phillipsburg: P&R Publishing, 2011), 65-66.
 This is expressed so well in Question and Answer 71 of the Larger Catechism: How is justification an act of God's free grace? Answer: Although Christ, by his obedience and death, did make a proper, real, and full satisfaction to God's justice in the behalf of them that are justified; yet inasmuch as God accepteth the satisfaction from a surety, which he might have demanded of them, and did provide this surety, his own only Son, imputing his righteousness to them, and requiring nothing of them for their justification but faith, which also is his gift, their justification is to them of free grace.”