Think of all Christ accomplished. He kept the prescriptive and penal requirements of the law. He took on human flesh and satisfied divine justice. He conquered death, sin, and the Devil. As the covenant-keeping Messiah, he won for his people every spiritual blessing (Eph. 1:3). Jesus Christ is wisdom, righteousness, sanctification, and redemption (1 Cor. 1:30).
Union with Christ
But how does all that Christ accomplished become ours? That’s a question most of have never considered. John Calvin asks:
How do we receive those benefits which the Father bestowed on his only-begotten Son—not for Christ’s own private use, but that he might enrich poor and needy men? First, we must 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 for us.
So how do we share in Christ’s benefits? Calvin’s answer: “The Holy Spirit is the bond by which Christ effectually unites us to himself.”11
In Romans 8:9–11, Paul argues along similar lines. When the Spirit dwells in us, we have the Spirit of Christ (v. 10), and if the Spirit is in us, we will have life in Jesus Christ (v. 11). In short, when you have the Spirit, you have Christ; and when you have Christ, you have the Spirit. The Holy Spirit unites us to Christ, because the Spirit is the Spirit of Christ. He is the Spirit of adoption, making us children of God the Father by joining us to Christ our brother (Rom. 8:15; Gal. 4:6; Heb. 2:17). God, by the Spirit, has torn the “first Adam” jersey from our backs and put us on the “second Adam” team.
We don’t often think about this aspect of redemption, but John Murray says that union with Christ is the “central truth of the whole doctrine of salvation.”12 So crucial is our union with Christ that Paul uses this “in Christ” language about 160 times.13 Justification, reconciliation, redemption, adoption, sanctification, glorification—all these belong to us because of our union with Christ. In a mysterious, supernatural way that transcends spatial categories, Christ is in us by the Spirit that we might have communion with Christ and share in all his benefits.
DeYoung, Kevin L. 2011. The Holy Spirit. Edited by D. A. Carson and Timothy J. Keller. The Gospel Coalition Booklets. Wheaton, IL: Crossway.