One of the most notable contributions of the Eastern Orthodox tradition to Christian theology is its strong emphasis on what they call theosis, or divinization. Without much exaggeration, one could say that it is the centerpiece of their whole theology, touching every feature of the faith, from daily life to the liturgy. For the Orthodox, salvation means not only forgiveness of sins and resurrection unto life in Christ, but also real participation in the life of God––a participation granted to human beings through the saving work of Christ and then dispensed through the sacramental ministry of the church.

They’ll often point to passages such as 2 Peter 1:4, which teaches that Christians become “partakers of the divine nature, having escaped from the corruption that is in the world because of sinful desire.” In the famous saying of St. Athanasius––the heroic defender of Christ’s divinity during the Arian controversy, and one of the architects of the Nicene Creed––“God became man so that man might become God.”

While this might sound strange or perhaps even dangerous to Christians not used to speaking in this way, the Orthodox don’t mean to teach that human beings become God in the way the Father, Son, and Spirit are God in the proper sense. Rather, in heavenly life, human beings will be drawn so close to the life of the Holy Trinity that they will be a party to the relationship the three persons share in eternity. One of the crucial ways the Orthodox choose to describe this relationship with God is the idea of Christ’s indwelling in the believer and the consequent gradual renovation of the soul. As St. Paul says, after all, “I have been crucified with Christ. It is no longer I who live, but Christ who lives in me” (Gal 2:20).

To be a Christian is not only to live in and for oneself, but to live in and through Jesus Christ––and therefore to live in service to the neighbor.

Similarly, many Christians of the Reformed or Calvinistic traditions will be very eager to speak about the indwelling of Christ in the Christian. At their best, the Reformed will speak very eloquently of this notion taken from Paul’s letters in terms of “union with Christ.” To be united to Christ in faith means that the believer has a special and inextricable connection to the Savior who has purchased him or her with His blood.

Speaking of union with Christ is biblical. Paul himself describes in graphic and exciting terms the implications of new life in Christ. To be a Christian is not only to live in and for oneself, but to live in and through Jesus Christ––and therefore to live in service to the neighbor. Having first gone through cross and resurrection for us, Christians are now really and truly incorporated into the death and life of Jesus. Because of this, faith means that Christ also lives in us (in nobis). Indeed, some recent scholars of Martin Luther have pointed out that his thought, especially in the 1531/5 Lectures on Galatians, includes a rich account of Christ’s real and true presence in faith (in ipsa fide Christus adest).

However, Christ’s presence in faith should not be discussed in the abstract without three additional clarifications. The first of these is that Christ’s presence in faith must always be tied to the external word of promise which is heard by the believer, especially in word and sacrament. Without a properly external grounding for Christ’s true presence in and with the Christian, there is a danger that we can come to claim Christ’s presence in us as if it were our own. After all, if it is Christ who lives in me, as Paul says, “It is no longer I who live” (Gal 2:20). If Christ lives in me, it means that I have died to my old sinful self on account of what Christ has done for me.

Luther warns in his Lectures on Galatians that there is a temptation to confuse Christ’s removal of our sins with our own works, thus making ourselves into gods––for it is God’s own nature to forgive sins. Discerning Christ’s presence for faith in the external word means we can’t take credit for it. Gerhard Forde once remarked that the more “forensic” justification is, the more “effective” (or real) it becomes. Likewise, one could say, the more external the word is, the closer I am drawn to Christ who lives in me by faith and His word.

A second clarification is that just as Christ dwells in me through His word and Spirit, so also do I dwell in Christ. Through baptism into His death (Rom 6:3), believers have been incorporated into the work of Christ in the cross and resurrection. These are events that have already been completed in history. Because Christ has accomplished salvation entirely outside of us in an objective and unqualified sense, we have confidence that our salvation doesn’t depend on some inner state of heightened spirituality or union with God, but on the objective work of Christ for you that is already finished (see John 19:30).

The third and final clarification that should be made in any discussion of union with Christ is that, just as Christ bestows on the believer all that belongs to him––righteousness, innocence, blessedness, and immortality––so also does Christ come to take from you all that is yours: death, sin, faithlessness, and wickedness. At His cross, Christ really and truly removes your sins and dies with them and for them. Because Christ has actually, and not only metaphorically, appropriated your sin (Gal. 3:13; 2 Cor. 5:21), He dies under the law’s just verdict of condemnation. In the cry of dereliction, Christ confesses not His severance from the Father but confesses His guilt under divine wrath given in the outpouring of the law. Like the priest in the temple, Christ’s exclamation from the cross is His confession of the sins of all people as if they were His own (Lev 16:21). Even though Christ is righteous and innocent on His own account, at the cross He bears all the sins of all people, for “the LORD has laid on him the iniquities of us all” (Isa 53:6). Christ and His Father are united in their desire to place sin and the condemnation of the law on Christ so as to remove it from the sinners they forgive. In the resurrection, Christ and the Father are vindicated in their fulfillment of the law on behalf of sinners, now forgiven and strengthened by the gospel.

Christ’s indwelling in the Christian must be tied relentlessly to these external and objective events of God’s own action.

Any discussion of the believer’s union with Christ must be clearly linked to the objective work of Christ in atonement and reconciliation that is now bestowed through the preaching of the gospel. This focuses union with Christ on what God does for us, not on an internal experience. Christ’s indwelling in the Christian must be tied relentlessly to these external and objective events of God’s own action. Otherwise, Christ’s union with the believer can become a speculative doctrine that funds the self-righteous tendency of the old creature to claim God’s works for himself or herself; or, it can undermine the assurance of God’s merciful and objective desire to forgive which word and sacrament so clearly communicate.