I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me. (Galatians 2:20, KJV)

Before beginning my commentary today, I would like to share a recent article from Tony Arsenal on this subject which does a superb job of explaining the life we have in Christ. You can find it at his blog here

We are not our own (1 Cor. 6:19). We are united to Christ through faith by the indwelling of the Holy Spirit.

Union with Christ is our life. John Murray once said it is “the central truth of the whole doctrine of salvation.” We are united to Christ both as our covenant head and through a mystical union.

Covenant Union

We are united to Christ both federally (in terms of covenant) and mystically (in terms of a personal bond). This union was established as Ephesians tells us “before the foundation of the world” (1:4).

Our federal union with Christ is evident in a number of places in Scripture but most notably in the 5th chapter of Paul’s Letter to the Romans. Here, Paul describes the effect of the fall in Adam, and the effect of redemption through Christ:

“For if by the one man’s offense many died, much more the grace of God and the gift by the grace of the one Man, Jesus Christ, abounded to many.” (Romans 5:15, NKJV)

When Adam lived in the garden, he stood as the representative of all men. He was in covenant with God and he broke that covenant. Christ came to fulfill the law and pay the price for Adam’s sin and the sins of us all. Through faith in him, we no longer are united to Adam as our federal head. Instead, we are united to Christ, and by his performance in the law and suffering in the crucifixion, he stands as a mediator to the Father for us. All that we have is in Christ.

Mystical Union

We also have a union with him mystically. Now, before any alarms go off, I don’t mean mystically in some superstitious or magical way. I mean it in the sense Calvin spoke of it, an unio mystica. Calvin says:

Therefore, that joining together of Head and members, that indwelling of Christ in our hearts — in short, that mystical union — are accorded by us the highest degree of importance. We do not, therefore, contemplate him outside ourselves from afar in order that his righteousness may be imputed to us but because we put on Christ and are engrafted into his body — in short because he deigns to make us one with him. – Institutes II. 16. 19

The federal union and the mystical union are distinct but they are not separate. Because He is the Head and we are the body, we may have union with him such that we partake of all the benefits of life in him. This is discussed in Westminster Larger Catechism Q69 which states that we have a “communion in grace” by which there is a “parktaking of the virtue of His mediation” in our “justification, adoption, sanctification, and whatever else in this life” may manifest our union with Him.

This question comes after the questions about the invisible church and the effectual call and immediately before the questions regarding justification, sanctification, and eternal life. What the catechism is teaching is that all that Christ accomplished through his incarnation, life, death, and resurrection gets applied to his elect through union with Him. It is through union with Him that we are pardoned from our sins by the righteousness of Christ (justification), we are sealed through the Spirit putting repentance unto life and strength to resist sin in us (sanctification), and the “communion in glory” of which we experience the first-fruits in this life and by which we receive eternal life (Ephesians 2:5-6, Colossians 3:3-4).

All of this flows from the person and work of Jesus Christ, the God-Man, the Word become Flesh, the Mediator. Our union with him makes possible all life and blessedness.

Calvin comments on this verse in the following way which succintly the mystical union we have with Christ:

Yet not I, but Christ liveth in me. This explains what he meant by “living to God.” He does not live by his own life, but is animated by the secret power of Christ; so that Christ may be said to live and grow in him; for, as the soul enlivens the body, so Christ imparts life to his members. It is a remarkable sentiment, that believers live out of themselves, that is, they live in Christ; which can only be accomplished by holding real and actual communication with him. Christ lives in us in two ways. The one life consists in governing us by his Spirit, and directing all our actions; the other, in making us partakers of his righteousness; so that, while we can do nothing of ourselves, we are accepted in the sight of God. The first relates to regeneration, the second to justification by free grace. This passage may be understood in the latter sense; but if it is thought better to apply it to both, I will cheerfully adopt that view. – Calvin, Commentary on Galatians 2

Importance of this Doctrine

So what is the importance of this doctrine? By it we know where to look for all of our salvation. By it we learn that there is nothing we can do to save ourselves. By it we know that our communion with God is not based on the work we do but on the work of Christ. By it we press on in grace to be obedient to God and to love and serve him according to His revealed will, not by the sweat of our brow or self-determination but by the Spirit of Christ dwelling within us.

By being united to the Son, you are united to the one who gives you life. I’ll end with a quotation from Athanasius which illustrates this glorious truth amongst the Early Church Fathers:

And thus, taking from our that which is like, since all were liable to the corruption of death, delivering it over to death on behalf of all, he offered it to the Father, doing this in his love for human beings, so that, on the one hand, with all dying in him the law concerning corruption in human beings might be undone (its power being fully expended in the lordly body and no longer having any ground against similar human beings), and, on the other hand, that as human beings had turned towards corruption he might turn them again to incorruptibility and give them life from death, by making the body his own and the grace of the resurrection banishing death from them as straw from the fire.  – On the Incarnation, p.67, 44A PPS, St. Vladimir’s Seminary Press

I am a Reformed Presbyterian. I offer all content as my own personal reflections. I am not a licensed minister.