Paul and Participation in Christ: An Introduction
Union with Christ is often said to be the central concept within Pauline theology.  Especially the theology of Calvin has put this concept at the center, which has the potential of harmonising the sometimes puzzling parts of Paul’s theology. But how do we even begin defining and understanding it without reverting to vague truisms? In this article I want to do five things:
- give an overview of important Pauline terms for this union and
- of important theological/systematic terms to describe it;
- summarise the meaning of the cross and resurrection of Christ and
- the way believers participate in it and in him; and
- put the transformation of believers in theological perspective.
1. Pauline Terminology
The words Paul uses to talk directly about union with Christ are κοινωνία (koinōnia, ‘fellowship’, ‘sharing’, ‘participation’), κοινωνέω (koinōneō, ‘to share, participate’) and κοινωνός (koinōnos, ‘partaker’, ‘sharer’).  Most basically, these terms denote a personal and communal participation in the single gift of Christ and the Spirit (to use Barclay’s language).
Paul also uses prepositions to describe the union between believers and Christ. (Note that I use the term ‘believers’ throughout the article to denote those who are now united with Christ, even when I’m talking about their conversion in the past.)
- Every human is born outside of Christ (χωρὶς Χριστοῦ chōris Christou; Eph 2:12) and in another system of participation, namely in Sin, Death and the Flesh (cf. Rom 6:1–8:7). This is the place ‘from’ (ἐκ ek) which we are rescued (Gal 1:3; Col 1:13). Through faith and baptism, believers move into (the realm of) Christ (εἰς Χριστὸν, eis Christon; Rom 6:3–4, Gal 3:27; cf 1 Cor 12:13).
- Now believers can properly be described as ‘in Christ’ (ἐν Χριστῷ, en Christōi). Paul uses this phrase or near synonyms (i.e., ‘in the Lord’, and also ‘in the Spirit’) dozens of times throughout all his letters. It describes Christ as the locus of believers’ existence. They have their being in the realm that is filled with and ruled by the crucified and risen Christ.
- In (the realm of) Christ, believers share things with (σύν syn) Christ. Paul often creatively uses this preposition as a prefix. 
- The faith of Christ is the origin of believers’ existence in Christ: they are from the faith of Christ (Rom 3:26; Gal 2:16; cf. Rom 4:16; Gal 3:7, 9). Believers live through (διὰ dia) Christ (1 Cor 8:6); they suffer for (hyper) Christ (Phil 1:29), and live in accord with Christ Jesus (κατὰ Χριστὸν Ἰησοῦν kata Christon Jēsoun; Rom 15:5).
Finally, Paul uses metaphors when talking about union with Christ, such as adoption into the family of Christ. This will be the focus of other articles.
2. Theological Terminology
‘Union’ is actually one word among others that theologians use to get at this concept. Others are:
- Representation — Christ represents believers as king
- Incorporation — believers are incorporated into (the community of) Christ
- Identification — believers identify with Christ
- Participation — believers participate in the life and story of Christ
These terms can be integrated if we consider the concept of Messiahship.  As Messiah, Jesus represents his people both in who he is and what he does. His realm overlaps with his people as the renewal of the cosmos still awaits consummation. This means that to be in the realm of Christ’s lordship means to have been incorporated into the people of Christ. As king, Jesus identifies with his people and his people with him in loving loyalty. Lastly, his people participate in his life and mission, which I will expand on below.
To further elucidate union with Christ, one can lay it out along the following dimensions: 
- Objective — the individual, unique Son of God, crucified and risen in history, present through the Spirit in believers and the church;
- Subjective — the individual believer participating in Christ through the Spirit, adopted as son, co-crucified and co-risen with Christ;
- Intersubjective — the corporate community of believers united to Christ and to each other in death and resurrection with Christ through the Spirit.
First I will discuss the objective dimension (part 3), before connecting this to the subjective and intersubjective dimensions (part 4). Lastly, I will highlight believers’ transformation in Christ from both an anthropological and theological point of view (part 5).
3. The Crucified and Risen Christ
At the heart of Paul’s theology is, indeed, the gospel of the crucified and risen Christ. This constitutes the ‘objective’, historical dimension. Christ was crucified, Christ was resurrected. A short discussion of the meaning of Christ’s work here is necessary.
First of all, one cannot separate the person from the work of Christ. What he does reveals who he is — indeed, who God is, which we will further touch on in part 5. Therefore, participation in the person of Christ inevitably means participation in the story of Christ, i.e., narrative participation (see Richard Hays).
Secondly, one must see the cross and the resurrection in apocalyptic or eschatological perspective. The cross deals with the present evil age, marked by the guilt of sins and slavery to the powers of Sin, Death, evil spiritual beings, the World and the Flesh. This age could be summarised as exile: away from God’s presence, humanity is enslaved and dehumanised, while still being held responsible for its participation in this system of oppression and evil. The resurrection, then, ushers in the blessed age to come, marked by justification, righteousness, the power of the Spirit of life, the rule of the Messiah, the restoration of creation and of individual embodied life (see table 1). This could be seen as the new exodus.
Thirdly, the cross paves the way for the resurrection. The present age must be dealt with in order for the age to come to arrive, and the way Christ does so is often called the ‘atonement’. There are various ways of talking about the atonement, but an important one is through the notion of sacrifice: Christ died for us. In love he took on himself the fate of Israel and of the world, which is exile. The judgment Israel deserved, and with it the world, fell on Jesus.  Paradoxically, this became the way to the resurrection. Death led to life; exile brought about exodus.
Christ was faithful to God and his God-given mission in loving others till death.
Fourthly, the cross not only leads to the resurrection but also defines resurrection life. The cross was both an act of faith(fulness) toward God and love toward human beings.  Christ was faithful to God and his God-given mission in loving others till death (Rom 3:21–26; Gal 2:15–21; Phil 2:5–11; 3:9) — not just others, but his very enemies (Rom 5:6–11). Moreover, the resurrected Christ remains the crucified Christ, which means that, to use Gorman’s terms, resurrection life is cruciform, namely, marked by faith and love. Although there will not be suffering in the age to come, there will be cruciformity. We are (newly) created in the image of the crucified Christ.
Fifthly, the resurrection validates the crucifixion: the crucified Messiah is the real Messiah. The one condemned by the people is justified by God as the eschatological king of the Jews (Rom 1:4; cf. 1 Tim 3:16). By raising him from the dead, God confirms that the crucified Jesus is really the locus of the people of God in the promised age to come. 
Sixthly, the resurrection empowers cruciformity in the overlap of the ages. Although the resurrection inaugurated the age to come, we still await its consummation at Jesus’ second coming. This is the ‘already-not-yet’ dimension of New Testament eschatology. In the overlap of the ages, believers are empowered by the resurrection (i.e., the presence of the risen Christ) to suffer with Christ in faithfulness to God, in love for others, and in hope of the coming glory and the resurrection of the body (thus completing the triad of faith, love, and hope). But now I’m getting ahead of myself.
Believers are empowered by the resurrection to suffer with Christ in faithfulness to God, in love for others, and in hope of the coming glory.
4. Individual and Corporate Participation through Pistis and Pneuma
The gospel of the crucified and resurrected Messiah does not remain objective. The crucified and resurrected Christ is living and present in the church through faith and through the Spirit. These two are integrated, even inseparable, realities: faith is produced by the Spirit, and the Spirit is the Spirit of cruciform faith. 
Faith unites Christ and saints narratively and missionally. Jesus was faithful and obedient in dying on the cross to liberate humanity. Through their own faith— i.e., belief, trust, fidelity/faithfulness — believers participate in this cross-and-resurrection story of Jesus.
First of all, through the faith of Christ, saints are reconciled with God and liberated from the powers of the present age (see above; cf. Rom 5:1–11; Gal 2:15–21). Christ’s faith, then, is the means of our justification. Our faith, on the other hand, is not a condition that one must meet in order to receive the benefits of Christ’s faith. Rather, it is elicited by the faith of Christ and is the mode of existence brought about by Christ’s faith.
Now, being reconciled, liberated and newly created ‘in Christ’, believers progressively embody and live out Christ’s faithfulness as they participate in the cross. This pistis consists of faithfulness toward God which is active in love toward others (Gal 5:6; cf. 5:22), both neighbour and enemy.
Thus believers continue Christ’s mission of the kingdom, even, or especially, amid suffering. This is what Paul gets at when he says that he ‘bears the scars of Christ’ (Gal 6:17) and ‘fills up what is still lacking in the afflictions of Christ’ (Col 1:24).  Moreover, this participation in the cross leads to the final redemption on the day of Christ and is empowered by the resurrection-life of the Spirit (see above on relation between cross and resurrection).
Human faith is therefore based on and arises from the objective work of Christ, but goes beyond that in filling out that work. Christ’s faith is both the source and the shape of the believer’s existence in Christ. It is both cruciform — that is, ‘faith working through love’ — and resurrectional — that is, empowered by the life-giving Spirit and leading to new experiences of life, both for self and others.
Christ’s faith is both the source (thus the benefits) and the shape (thus the participation) of the believers’ faith.
The Spirit, then, unites Christ and believers existentially or mystically: the Spirit is the Spirit of Christ (Rom 8:9; Gal 4:6; Phil 1:19) and ‘the Spirit of him who raised Jesus from the dead’, indeed, the very glory and power of God (cf. Rom 6:4; 1 Cor 6:14). This is what systematic theologians referto with inseparable operations: where the Spirit is at work, so are the Father and Son, and vice versa. Thus, Christ too is said to live in believers (Rom 8:10; 2 Cor 13:5; Eph 3:17; Col 1:27), while the presence of the Father can be deduced (cf. 1 Thes 1:1; 2 Thes 1:1). (The latter is a Johannine notion; see Joh 14:23; 1 Joh 4:4, 15–16; cf. Joh 10:30).
So, not only are believers in Christ, Christ is also in believers. Precisely because they are indwelt by the Spirit of the Son, believers are conformed to the person and story of the Son. Christ’s thoughts become their thoughts (1 Cor 2:16; cf. Rom 8:5–7; 12:1; Eph 4:23; Phil 2:5), Christ’s affections become their affections (Phil 1:8; cf. 2:1), and Christ’s practices become their practices (e.g., Phil 2:3–11). This conformity is not just imitation; believers actually embody and enact Christ’s faith. Believers are Christ-agents because Christ works in and through them through his indwelling Spirit.
Conformity to Christ is not just imitation; believers actually embody and enact Christ’s faith.
Therefore, while faith concerns the work of Christ and believers, the Spirit entails the person of Christ and believers. To use philosophical terms, the first is functional, the second ontological.  Lastly, faith and the Spirit, cross and resurrection, come together in the corporate, participatory rites of baptism and the Lord’s Supper.
5. Transformation: Wholeness and Theosis
Therefore, both missionally and mystically, believers are united with the Son of God and, in this union, are transformed through the Spirit. This transformation in Christ can be approached from two angles. Working from the concepts of the image of God and the incarnation, Jesus is the archetypical Human, the new Adam who represents the new — and true- humanity, the Messianic philosopher-king who represents the new Israel. He embodies human faithfulness to the covenant and the covenant God in loving others to death, thus showing that cruciformity is at the heart of what it means to be human. Therefore, as believers come to share more and more in the cruciform Christ, they become more human.
Secondly, considered from the perspective of the Trinity and the hypostatic union, Jesus is the self-revelation of God. He does not just show who God is as in a mirror, but as in a face-to-face encounter. He embodies God’s covenant faithfulness and love for Israel and the world, not merely as an agent of God but as God himself.  He shows what it means to be God, namely cruciform, kenotic love. As Paul says in Colossians 2: “For in Christ all the fullness [plērōma] of the Deity lives in bodily form” (Col 2:9). Paul then connects this Christ-full-of-Deity with believers: “and in Christ you have been filled [peplērōmenoi]” (cf. Eph 1:23; 3:16–17, 19). In other words, because God is in Christ, and we are in Christ, God is in us. This mind-blowing reality means that in the embodied forms of individual and corporate Christ-life, the fullness of God is present. Believers are filled to the brim with God.
In the embodied forms of individual and corporate Christ-life, the fullness of God is present.
Thus, in union with Christ, believers do not merely become whole as human beings, but they do so as they participate more and more in God. This process is historically called theosis.  At the center of this all is the image, the ikōn, of the crucified and resurrected Christ. To be human is to be like him; to be like him is to be like God, and to be like God is to be cruciform. 
To sum up, participation in Christ is narrative and eschatological, pistological (to coin a term) and pneumatological, cruciform and resurrectional, humanising and theotic. Christ, and participation in him, is, indeed, at the heart of Paul’s thought and holds it all together. 
 Cf. the recent work on Paul by Douglas J. Moo, A Theology of Paul and His Letters. See also Michael J. Gorman, Participating in Christ: Explorations in Paul’s Theology and Spirituality.
 Rom 12:13; 15:26, 27; 1 Cor 1:9; 10:16, 18, 20; 2 Cor 1:7; 8:4, 23; 9:13; 13:14; Gal 2:9; 6:6; Phil 1:5; 2:1; 3:10; 4:15; Phm 1:6, 17. The relative importance of these terms in Philippians and Philemon is significant.
 For example, in Romans 6, Paul coins the terms συσταυρόω (systauroō, ‘co-crucify’; 6:6), συνθάπτω (synthaptō, ‘co-bury’; 6:4) and συζάω (syzaō, ‘co-live’; 6:8). Moreover, in Romans 8, Paul talks about being ‘co-heirs’ (συγκληρονόμοι sygklēronomoi), ‘co-suffering’ (συμπάσχω sympaschō) and being ‘co-glorified’ (συνδοξάζω syndoxazō). Other examples are Gal 2:20; Eph 2:5–6; Col 3:1.
 See the magnificent section on Christology in N.T. Wright, Paul and the Faithfulness of God, ch. 9.
 See Constantine R. Campbell, Paul and Union with Christ: An Exegetical and Theological Study, and the collection of essays edited by Thate, Vanhoozer and Campbell, ‘In Christ’ in Paul: Explorations in Paul’s Theology of Union and Participation.
 Cf. Wright, Paul and the Faithfulness of God, 825: ‘Jesus, a Messiah, has drawn together the identity and vocation of Israel upon himself’ (italics original). Wright also wrote very helpfully about this connection in Jesus and the Victory of God.
 Gorman has argued this extensively throughout his works; see especially the section ‘Christ’s Death as the Quintessential Covenantal Act’ in Inhabiting the Cruciform God: Kenosis, Justification, and Theosis in Paul’s Theology, ch. 2.
 See the final chapters of N.T. Wright, The Resurrection of the Son of God.
 This is the same (paradoxical) relationship as between cross and resurrection: cruciformity leads to experiences of life (in the Spirit), while the (Spirit of the) resurrection empowers cruciformity (= faith).
 This does not mean that Paul is reconciling himself or liberating himself. Rather, he is experiencing and embodying this very reconciliation and liberation of God and thus becomes an agent of that reconcilation and liberation. If non-believers would see Paul in his faith and love even amid suffering, they would see a walking and breathing image of Christ. In other words, they would see cruciformity and Christoformity. Cf. Gorman, Becoming the Gospel: Paul, Participation, and Mission.
 This does not mean at any point that the lines between God’s being and believers’ being are blurred. At no point does God become believer or believer become God in such a way that their existences merge. However, as Calvin argues in his Institutes, this is a union (as intimate as it is!) not of natures but of persons, as in the communion of marriage (cf. Gen 2:24 and Eph 5:30–1).
 See N.T. Wright, Jesus and the Victory of God, ch. 13.
 See Gorman, Cruciformity (2021), in the afterword: ‘To be cruciform is to be Christlike, which is to be both more like God and more fully human.’ See also Inhabiting the Cruciform God and Participation in Christ.
 Cf. ch. 2 in Gorman, Participating in Christ: ‘The Cross: Revelation of Christ and God, of Humanity and the Church’.
 Cf. Douglas Campbell’s description of his PPME model in The Quest for Paul’s Gospel, 41–2, which contains most of these dimensions: “In sum, this process [of participation] is real and concrete, radically transformational, unconditional, relational — and quite intimately so — and trinitarian. It is also eschatological, that is, denoting entry into the second age or ‘the age to come’. (…) [T]he participatory dimension noted here can in my view be usefully glossed by ‘pneumatological’ (…). [T]he Holy Spirit enables participation in a martyrological set of events focused on Christ and his cross and crucifixion, as well as in the resurrection. (…) So the entire conception can be known as PPME: pneumatologically participatory martyrological eschatology.’