Union and Communion: A Theology of the Christian Life

[Note: This sermon is based and adapted from the paper I wrote for my Theology of Christian Life and Worship class, which is part of my ThM studies at Asia Graduate School of Theology.]

Introduction: The Beginning of the Christian Life

It is not surprising that the unregenerate are preoccupied with one’s self, even promoting an inflated ego as a virtue. It is lamentable, though, that even “Christian practice is often marred by self-absorption,” as John Webster observes.[1] In our thinking about the Christian life, we make it more about us Christians and what we do with our life than about anything else. A theology of the Christian life, however, must begin—and end—not with the Christian or how we must live, but with God, “who alone has immortality, who dwells in unapproachable light” (1 Tim. 6:16 ESV). God alone enlivens and defines the Christian life.

We owe our regenerate life to his life-giving grace. We did nothing to earn or merit life. We can do no saving good in our spiritual deadness. “When we were dead in trespasses, [God] made us alive together with Christ” (Eph. 2:5) out of sheer grace and mercy. The life we now have is Christ himself, “In him was life, and the life was the light of men” (John 1:4). Cast out of the Garden, we “who once were far off have been brought near by the blood of Christ” (Eph. 2:13). Thus the Christian life begun. Not us gasping for air to revive ourselves, but fully alive by the Spirit. Not us crawling our way back to God, but fully reconciled because of the peacemaking work of Christ on the cross. Not us trying to repay our insurmountable debts and proving ourselves worthy, but fully clothed with Christ’s perfect righteousness.

Our regenerate life is a work of God’s re-creative power (2 Cor. 5:17), his light-shining grace. We were blind, unable to see “the light of the gospel of the glory of Christ, who is the image of God” (2 Cor. 4:4). But now we see clearly (though not yet fully but still “in a mirror dimly,” 1 Cor. 13:12) because of God’s “Let there be light, and there was light” power switching on the eyes of our hearts, giving us “the light of the knowledge of the glory of God in the face of Jesus Christ” (2 Cor. 4:6).

A theology of the Christian life anchored in the good news of the life and light we have in the Lord Jesus Christ will prevent us from sinking into the Slough of Despond on our way to the Celestial City, like Christian in John Bunyan’s The Pilgrim’s Progress. Although totally forgiven, yet we remain sinners—simul justus et peccator. And as sinners, we will fail. Yes, both mortification and vivification are what we do, but there are not a few occasions that we will fail or fall short of killing sin and practicing Christ-like virtues. But as John Webster reminds us, they are “good works: human practices which proceed from trust in the completed work of God.”[2] The good news of the gospel is not according to our own performance, but in God’s finished work, “that God is for us in spite of our failure.”[3] Our confidence, then, in living the Christian life is not in ourselves and in who we are, but in Christ and who Christ is for us. There is no need for us to look for anyone or anything else for assurance and power in living the Christian life. So, we sing, “In Christ the Solid Rock I stand, all other ground is sinking sand.”

Nothing for me encapsulates better the theology of the Christian life than Paul’s statement in 2 Corinthians 3:18, “And we all, with unveiled face, beholding the glory of the Lord, are being transformed into the same image from one degree of glory to another. For this comes from the Lord who is the Spirit.” This is a theology not for a unique group of Christians, but for all Christians (“we all”). This life begins in regeneration, as the Spirit imparts new life in us, enabling us to see the glory of Christ in the gospel (“with unveiled face”). This life continues throughout our journey in this world (“being transformed”). This life involves a change toward Christlikeness, mortification (putting off the old life) and vivification (putting on the new life in Christ) (“into the same image from one degree of glory to another”). This change happens not through our own self-willed effort, but by the transforming grace of God (“this comes from the Lord who is the Spirit”). The means God uses to effect that transformation is the gazing upon or the heart-contemplation of the glory of Christ in the gospel (“beholding the glory of the Lord”).

So, the Christian life is that life that flows out of a believer’s union with Christ drawing him into closer communion with the Triune God, and together with the church as God’s people contemplate the glory of the person and work of Christ and commend the same to the rest of creation by the indwelling presence and power of the Spirit. I will attempt to unpack that thesis for the rest of this paper.

Identity: Living in Union with Christ

Before asking, What must I do as a Christian?, we must first ask, Who am I?, or more precisely, To whom do I belong? Before talking about the Christian life as activity, we must first settle in our minds and stand on the truth of our identity. This is why the Heidelberg Catechism’s answer to the first question (“What is thy only comfort in life and death?”) is “That I with body and soul, both in life and death, am not my own, but belong unto my faithful Savior Jesus Christ…”

So, the Christian life is that life that flows out of a believer’s union with Christ. The formulaic “in Christ” sums up the primary marker of Christian identity. This phrase (including “in him,” “with him” and other similar expressions) is prominent in Pauline theology. The Christian life, with all the riches of the blessings God bestowed on us, is flowing out of that mystical union with Christ. We live the Christian life not to attain to that reality, but as a living out of that reality. According to Webster, “Regenerate life means being alive together with Christ; it is life in him.”[4]

Ziegler notes, “The form and substance of discipleship is entirely derivative of the identity and saving work of the living Lord Jesus Christ.”[5] That is, imperatives in living the Christian life flow out of gospel indicatives. Paul follows this indicative-imperative pattern in the general structure of some of his letters. In his letter to the Romans, he spent 11 chapters discussing the gospel of grace before talking about the Christian life in response to “the mercies of God” (Rom. 12:1) in chapters 12-16. In Colossians, after expounding on the supremacy of Christ over all things and his sufficiency as anchor for Christian identity in the first two chapters, he spent the last two talking about how to live a life in view of our being “raised with Christ” (Col. 3:1), in light of our life that is “hidden with Christ in God” (v. 3) and in anticipation of “Christ who is your life” (v. 4). In Ephesians, he spent the first three chapters talking about the mystery of the riches of the grace we have received in Christ before urging them in the next three “to walk in a manner worthy of the calling to which you have been called” (Eph. 4:1).

Though 1 Corinthians doesn’t strictly follow that pattern, it is evident through and through that Paul believes that the solution to the schisms, sexual immoralities, disorderly worship, and doctrinal confusions plaguing the church is a constant reminder of the gospel of Jesus Christ. His exhortations are anchored in the “folly” of that message which alone has the power “to save those who believe” (1 Cor. 1:21). For at the heart of that message is the person of “Christ the power of God and the wisdom of God” (v. 24). Our Christian life is “entirely derivative” of what Christ has done and who we are in him: “And because of him you are in Christ Jesus, who became to us wisdom from God, righteousness and sanctification and redemption” (v. 30). That is why Paul reminds them again and again to “stand” on this gospel, “to hold fast” to it not just as something we need at the start of the Christian life, but as a daily necessity—for by this gospel we are “being saved” (15:1-2). That is why the message of the life, death and resurrection of Jesus is “of first importance” (v. 3) for the church and for every individual Christian, even for someone as advanced in the faith like Paul.

Paul’s concise statement of the Christian life in Galatians 2:20 should be the mantra of every Christian. The life we “now live” flows out of that union with Christ, not just us being in Christ (“crucified with Christ”) but Christ being in us (“Christ who lives in me”). That union is made possible by Christ’s completed work on the cross (“who loved me and gave himself for me”), and our life is energized by continually remembering that reality by faith. The Christian life is not primarily about us following Christ, but an overflowing of the life of Christ in us. Macaskill is on point, “The only thing that will break this cycle of self-centeredness is asking the right question: not ‘What can I do?’ but ‘Who can deliver me?’ The same Jesus by whom sin’s debt is canceled is the one by whom its power is broken.”[6]

Worship: Living in Communion with the Triune God

Sin is deadly, only the life we have in Christ can break its power. Our ultimate goal, however, is not breaking free from sin, but breaking into fellowship with the triune God. The Christian life is that life that flows out of a believer’s union with Christ drawing him into closer communion with the Triune God. Created in God’s image, we are called not merely to be his representation or reflection here on earth, but primarily toward communion with God in the Garden. After expelling humans from the Garden of that communion, God set in motion a plan to draw his creatures back to fellowship him. This he accomplished when the curtain in the temple was torn into two as Christ breathed his last on the cross. God goes to great length in accomplishing our redemption because “the plan of God for his creation is the marriage of all of God’s people with God in Christ by the Holy Spirit.”[7]

We are called to participate in the dance of Trinitarian love. The Father set his love on us from eternity past, the Son redeemed us on the cross, and the Spirit applies that redemptive work in our hearts (1 Pet. 1:2; Eph. 2:18) in order to bring us to God (1 Pet. 3:18). God is the ultimate goal of the gospel and, therefore, of the Christian life. If God is our goal—not the good life by worldly definition but communion with God as our highest good—then a properly oriented Christian life is fastened to that goal. Mortification’s goal is not achieving victory over sin, but tasting the sweetness of divine fellowship. Vivification’s goal is not showcasing one’s transformation or achievement, but being satisfied with the full and unending joy of the nearness of God’s presence (Psa. 16:11).

Discipleship cannot be confined to following a program, or completing a curriculum, or developing godly habits. Discipleship is following a Person. But it is not following Jesus at a distance (though he is considerably far ahead of us in his perfections), but in close communion with him. John Yoder clarifies, “Following Jesus is the result, not the means, of our fellowship with Christ.”[8] Like branches to a vine, we abide in Christ, remaining attached to his life-giving and life-sustaining grace. For apart from him we can do nothing (John 15:4-5). Living the Christian life in close communion with the Son helps us avoid running on empty. Instead of trying to manufacture strength from our own limited resources, we cling to the infinite resources we have in Christ (Eph. 1:3; 2 Pet. 1:3). Like sheep, we listen to the voice of the Good Shepherd, follow his lead, and feast on his provision. As members of his body, we submit to him as our Head and follow his wise leadership. As bride to our Groom, we gladly put ourselves in a position to fully receive from his sacrificial and purifying love.

Following Christ our Mediator draws us closer in communion with the Father as well. Experiencing more of the Father’s love as one walks in love and obedience, Jesus promised, “We (that is, the Father and the Son) will come to him and make our home with him” (John 14:23). Meditating on the grace and fulness of our adoption, we stay at home, not loitering on the hall of this world’s pleasures but enraptured by the sweetness of the Father’s embrace. As we grow in maturity, we are not like children learning to be independent as they enter adulthood. Rather, our growth is toward greater dependence to the Father. We cleanse ourselves from everything that defiles us and pursue holiness in filial fear as we hold on to and desire more of the reality of his promise to make his dwelling among us and walk with us as his sons and daughters (2 Cor. 6:16-7:1).

“For we are the temple of the living God” (v. 16). God dwells within and communes with us through his Spirit. Our bodies are blood-bought that it might be a temple, the Spirit taking permanent residence in us (1 Cor. 6:16). So, we live in light of that astonishing reality. We mortify sexual sins not to enter into that reality but because of that reality. There is a sense that the ministry of the Spirit is greater than the Son’s incarnation. Jesus—the Immanuel, God with us—said so himself that it is better for him to go away that the Spirit—God in us—might come.

This is the profound mystery and gracious reality of the Christian life. Not only that we sinners and all may find pardon through the blood of Jesus, but more so that we may draw near in communion with the triune God. This is why we worship and live our lives in light of that reality. Todd Billings said, “Worship shifts our attention to the mystery of the triune drama of being united to Christ, dwelling in the home of his Word and his love as we bear fruit as his disciples; this is the mystery of the triune God working in and through Christian love, service, and witness in the world.”[9]

Community: Living in Communion with the People of God

There is a sense that some contemporary and popular versions of Christianity have turned the Christian life into a private relationship with God. Our goal is intimacy with God, sure. But that relationship, though personal is never private. That is why a recovery of a trinitarian framework for a theology of the Christian life is crucial. The Trinity is one God but not alone and never alone even pre-creation. Created in the image of the triune God, we are saved by the triune God to dwell in communion with the triune God and together with the church as the people of God. Even the most introverted Christian knows that he cannot live his life in isolation and experience a vibrant one-on-one relationship with God. Billings reminds us, “To be in communion with the beautiful, alluring Christ is impossible without communion with his broken and sinful—yet cleansed and redeemed—bride, the church.”[10]

Human relationships are fractured at the fall. God’s redemptive work includes healing that divide—whether personal, domestic, or racial—through gospel of the Prince of Peace (Eph. 2:14-16). Like broken mirrors, we cannot fully reflect the image of God alone and in isolation. We cannot live the Christian life without other Christians in close proximity to us. We cannot do “one another’s” (love one another, bear with one another, encourage one another, etc.) without the other. Our individual bodies are temples of the Spirit, so is the church as a corporate body. “You (the plural you, not the singular) are God’s temple” (1 Cor. 3:16-17), Paul reminds the church being divided by schisms, pride, and conflicts.

Christ’s achievement on the cross is not just for our reconciliation with a holy God but also with our fellow sinners. Most of our deepest wounds are caused by other sinners. Fearful of taking the risk of experiencing further hurts, some Christians hesitate to invest themselves fully in relationships with other people. But it is to think only of relationship as one of the goals or aspects of our sanctification, and to forget that relationships particularly in the church are God’s means for our sanctification. Our communion with our fellow saints and sinners is both a living out of the reality and means of experiencing more of our communion with the triune God—as we forgive and love others as God’s beloved children, as we pour our lives in Christlike sacrificial service to others (Eph. 4:32-5:2) and as we let others partake of some of the fruit of the Spirit in our lives (Gal. 5:22-23).

Some professing Christians can rest content and for a long time absenting themselves from the assembly of other believers. When confronted, they are quick to justify that they can read the Bible and pray by themselves, and even watch worship from the comforts of their homes, as if that is all that God commanded us to do. However, no individual can truly read the Bible rightly, theologically, and experientially without the community of other believers—local and catholic. To isolate one’s self is to continue to wallow in the mire of self-centeredness, which is one root cause of our sinfulness, doing what is right in our own eyes.

Rhythm: Contemplation and Commendation

Since we have an eye problem, we need an eye correction—to have the eyes of our hearts enlightened (Eph. 1:18). To live the Christian life in close communion with God and his people, we have to cease looking inwardly but outwardly—vertically as we behold the beauty of Christ and horizontally as we commend that beauty to others. Thus, the last part of my thesis: The Christian life is that life that flows out of a believer’s union with Christ drawing him into closer communion with the Triune God, and together with the church as God’s people contemplate the glory of the person and work of Christ and commend the same to the rest of creation by the indwelling presence and power of the Spirit.

Contemplation and commendation form the daily rhythm for a believer. As “creatures of the Word” God is shaping us into the likeness of his Son as we gaze upon him in the Scriptures—the Old Testament preparing, promising, and pointing to Christ and the New Testament presenting, proclaiming and anticipating Christ. We commend his beauty to others as we prayerfully proclaim his excellencies (1 Pet 2:10) to unbelievers, disciple other believers by reminding them of the gospel, and lives our lives in such a way that “in everything [we] may adorn the doctrine of God our Savior” (Tit. 2:10).

Yet, as we have already seen earlier, this rhythm of contemplation and commendation cannot be accomplished in isolation, but most powerfully in community. The weekly assembly of the church as God’s covenanted people is one of God’s powerful means of grace in the life of a Christian. Removing one’s self from that life-giving source is a form of self-deprivation and, therefore, self-destructive. Though the amount of time we spend together every Sunday is limited, it is “both densed and charged…packed with formative power.”[11]

We are “a people held together by Christ’s beauty.”[12] As individual temples gather as one Temple on Sunday morning, we are held together by one desire, that we may “dwell in the house of the Lord” all the days of our lives, “gazing on the beauty of the Lord, and seeking him in his temple” (Psa. 27:4 CSB). As the eyes of our hearts, our social imaginaries, are captivated day by day by the deceitful and fading beauties of the world, a regular re-calibration of our heart vision is essential. What happens in corporate worship is not meant to be a performance of a few, but a re-enactment of the drama of the gospel as our spirits and bodies engage in adoration, confession, receiving assurance of pardon, thanksgiving, petition, receiving instruction, and communion.[13] God’s script gives direction and sets the agenda to this dramatic event as we together as one people sing the Word, pray the Word, listen to the preaching of the Word, and see the Word in the ordinances of baptism and the Lord’s Supper.

How can the self-absorption in our Christian practice be corrected? According to Webster, “One of the instruments for correcting these disorders in Christian living is attention to Christian teaching about God’s being and works, for such teaching draws the mind away from preoccupation with Christian practice and invites contemplation of God.”[14] God-exalting, Christ-centered preaching accomplishes this. According to David Mathis, “The best of preaching serves the worshiper in the joy of self-forgetfulness” by “tapping into the very power of preaching, namely, a preoccupation with Jesus,” “[swallowing] up the listener again and again not with self or the speaker, but with Jesus and his manifold perfections.”[15] When preachers represent the God of the Word as they re-present the Word of God, we “encounter God through his word.”[16]

The drama of God’s redemptive work in and through the Word is not just heard but seen in baptism and the Lord’s Supper. We participate in the drama presented in baptism not just during our own baptism but also by watching others get dipped into the waters. We contemplate the excellencies of Christ as we remember our baptism as signifying and sealing our union with Christ in his death and resurrection, spurring us to “consider [ourselves] dead to sin and alive to God in Christ” (Rom. 6:11). In baptism we hear anew God’s irrevocable promise confirming “through his Spirit and his covenant community that he has covenanted with the believer.”[17]

As baptism as a one-time act marks our entrance into God’s covenant community, so the Lord’s Supper is a continuous reenactment of gospel drama. Billings rightly calls it “as an icon of the gospel.”[18] as “we encounter God’s word in Christ in a form that we can taste and see.”[19] In the Supper, “The Spirit enables the church to enact its true identity” as being united to Christ, who then “offers his own person, his very presence, to his people, those who are hopelessly incomplete without him.” The Supper enables us to “enjoy a foretaste of heavenly manna, a taste that deepens our hunger and focuses our desires on the kingdom that only Jesus Christ can bring.”[20]

In the Word preached, reenacted, sung, and prayed every Sunday morning, we are enabled to take a glimpse of the glory of Jesus. As we spend time in contemplation, we practice commendation of his beauty to others as we sing with the church, pray with the church, and let the word “reverberate” in the life of the church throughout the week.[21] The gospel in the life of the church shapes how we practice meaningful membership and loving discipline, rejoicing with those who rejoice and grieving with those who grieve, giving and receiving, in a display of a broken yet beautiful church.

This, according to Herman Witsius, is the character not just of a true theologian but a true Christian—one who concerns himself with “the devout contemplation of God and His Christ,” and “[declaring] and [extolling], not in words only, but by the whole course of his life, the wonderful excellencies of God and thus lives entirely for His glory.”[22]

Conclusion: The End of the Christian Life

The Christian life presented and envisioned here is that life that flows out of a believer’s union with Christ drawing him into closer communion with the Triune God, and together with the church as God’s people contemplate the glory of the person and work of Christ and commend the same to the rest of creation by the indwelling presence and power of the Spirit. As beautiful as that portrait is, we all fully know that that life lived here on earth—in this fallen world—is by no means an easy life. Miseries and afflictions abound. Then one day, we will die (unless the Lord returns first). But in death, our life will not end. Our confessional identity, “We are not our own but belong to our faithful Savior Jesus,” is “both in life and death” our only comfort (Heidelberg Catechism Question 1). “For if we live, we live to the Lord, and if we die, we die to the Lord. So then, whether we live or whether we die, we are the Lord’s” (Rom. 14:8).

When we die, our life in Christ continues, and we are transformed from glory to glory. Our faith will turn into sight. Glimpses of his glory will be turned into an unending spectacle of the majesty of Christ. Our foretastes of the life of Christ now will be turned into a feast in the banquet table of the Lord’s goodness. As we see Jesus face to face, we will taste of his sweetness for all eternity, and be fully changed in his image, “forever rapt in wonder, love, and praise.”[23] “For from him and through him and to him are all things. To him be glory forever. Amen” (Rom. 11:36).

[1] John Webster, “Communion with Christ: Mortification and Vivification,” in Kent Eilers and Kyle C. Strobel, eds., Sanctified by Grace: A Theology of the Christian Life (Edinburgh: T&T Clark, 2014), chap. 8.

[2] Ibid.

[3] Ian McFarland, “The Saving God,” in Kent Eilers and Kyle C. Strobel, eds., Sanctified by Grace, chap. 8.

[4] Webster, “Communion with Christ,” in Kent Eilers and Kyle C. Strobel, eds., Sanctified by Grace.

[5] Philip Ziegler, “Discipleship,” in Kent Eilers and Kyle C. Strobel, eds., Sanctified by Grace, chap. 11.

[6] Grant Macaskill, Living in Union with Christ: Paul’s Gospel and Christian Moral Identity (Grand Rapids: Baker Academic, 2019), chap. 5.

[7] Matthew Levering, Engaging the Doctrine of Marriage: Human Marriage as the Image and Sacrament of the Marriage of God and Creation, Engaging Doctrine Series (Eugene: Cascade, 2020), Introduction.

[8] Cited in Ziegler, “Discipleship,” in Kent Eilers and Kyle C. Strobel, eds., Sanctified by Grace, chap. 11.

[9] J. Todd Billings, Remembrance, Communion, and Hope: Rediscovering the Gospel at the Lord’s Table (Grand Rapids: Eerdmans, 2018), chap. 1.

[10] Ibid., chap. 6.

[11] James K. A. Smith, Desiring the Kingdom: Worship, Worldview, and Cultural Formation, Cultural Liturgies, Vol. 1 (Grand Rapids: Baker Academic, 2009), chap. 5.

[12] Kent Eilers and Kyle C. Strobel, eds., Sanctified by Grace, intro.

[13] Bryan Chapell, Christ-Centered Worship: Letting the Gospel Shape Our Practice (Grand Rapids: Baker Academic, 2017).

[14] Webster, “Communion with Christ,” in Kent Eilers and Kyle C. Strobel, eds., Sanctified by Grace.

[15] David Mathis, Habits of Grace: Enjoying Jesus through the Spiritual Disciplines (Wheaton: Crossway, 2016), chap. 15.

[16] Jason C. Meyer, Preaching: A Biblical Theology (Wheaton: Crossway, 2013), chaps. 1, 17.

[17] Brandon C. Jones, Waters of Promise: Finding Meaning in Believer Baptism (Eugene: Pickwick, 2012), chap. 1.

[18] Billings, Remembrance, Communion and Hope, chap. 1.

[19] Ibid., chap. 2.

[20] Ibid., chap. 6.

[21] Jonathan Leeman, Word-Centered Church: How Scripture Brings Life and Growth to God’s People (Chicago: Moody, 2017).

[22] Cited in Joel Beeke, Reformed Preaching: Proclaiming God’s Word from the Heart of the Preacher to the Heart of His People (Wheaton: Crossway, 2018), 252.

[23] “A Reforming Catholic Confession,” https://reformingcatholicconfession.com/, accessed May 18, 2021.


Beeke, Joel. Reformed Preaching: Proclaiming God’s Word from the Heart of the Preacher to the Heart of His People. Wheaton: Crossway, 2018.

Billings, J. Todd. Remembrance, Communion, and Hope: Rediscovering the Gospel at the Lord’s Table. Grand Rapids: Eerdmans, 2018.

Chapell, Bryan. Christ-Centered Worship: Letting the Gospel Shape Our Practice. Grand Rapids: Baker Academic, 2017.

Eilers, Kent and Kyle C. Strobel, eds. Sanctified by Grace: A Theology of the Christian Life. Edinburgh: T&T Clark, 2014.

Jones, Brandon C. Waters of Promise: Finding Meaning in Believer Baptism. Eugene: Pickwick, 2012.

Leeman, Jonathan. Word-Centered Church: How Scripture Brings Life and Growth to God’s People. Chicago: Moody, 2017.

Levering, Matthew. Engaging the Doctrine of Marriage: Human Marriage as the Image and Sacrament of the Marriage of God and Creation. Engaging Doctrine Series. Eugene: Cascade, 2020.

Macaskill, Grant. Living in Union with Christ: Paul’s Gospel and Christian Moral Identity. Grand Rapids: Baker Academic, 2019.

Mathis, David. Habits of Grace: Enjoying Jesus through the Spiritual Disciplines. Wheaton, IL: Crossway, 2016.

Meyer, Jason C. Preaching: A Biblical Theology. Wheaton: Crossway, 2013.

Smith, James K. A. Desiring the Kingdom: Worship, Worldview, and Cultural Formation. Cultural Liturgies, Vol. 1. Grand Rapids: Baker Academic, 2009.

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