Critics claim that punishing an innocent person, even if they are willing, is unjust.  On the surface this objection seems to have some credibility.  For one of the pillars of Christianity is the sinless life of Jesus Christ.  In the Scriptures, Jesus, assured of his perfection, invites anyone to point out anything in his life that was sinful – the response was silence (John 8:46).  Given that Jesus lived a perfect life, “how can it be just to punish a righteous man for the sins of many unrighteous people?”[1]

It should be noted that Scripture confirms that “acquitting the guilty and condemning the innocent” (Proverbs 17:5) is repugnant to the Lord.  The concern of the critics is valid.  The willingness of Jesus alone is not enough to justify him going to the cross in our place.  Knowing that Scripture does not contradict Scripture and affirming the biblical teaching of penal substitutionary requires that a deeper explanation must exist if this objection is going to be refuted.

The answer that silences the critics is found in the biblical understanding of union with Christ.  “Union with Christ,” Jerry Bridges explains, “is that in a spiritual but nevertheless real way we [those who have saving faith] are united to Christ both legally and vitally.”[2] Based on this biblical truth Christ is not simply a third party mediating an exchange between God and sinners.  Instead there is a real union between Christ and those who have faith in Christ.  The magnitude of this truth can be seen as it is central in Johannine and Pauline literature.[3]

This union explains how Christ could be punished justly.  He is not judged for his own sins because he has no sins.  Instead, “he is judged for other’s sins, which, by virtue of their union with him, become his.”[4] This doctrine is in no way pronouncing that Jesus himself sinned.  Instead it is saying Christ is legally united with the sinner’s sins, thus he can justly be punished.  Therefore, the sinner’s union with Christ, which happens by grace alone through faith alone, explains how it is just for Christ to pay the price for sins he did not commit.  Justification is not merely legal fiction:

“[God] reckons righteousness to them, not because he accounts them to have kept his law personally (which would be a false judgment), but because he accounts them to be united to one who kept it representatively (and that is a true judgment)”^[5]

On the flip side, union with Christ explains how sinners can be made righteous – by faith, sinners are one with Christ and his righteousness becomes their righteousness.  In 2 Corinthians 5:21, Paul sums up this dual sided exchange: “For our sake he [God] made him [Jesus] to be sin who knew no sin, so that in him we might become the righteousness of God.”  The doctrine of the union with Christ boils down to this:  Christ rightfully takes what is the sinner’s (sin); the sinner rightfully receives what is Christ’s (righteousness).  The doctrine of union with Christ eliminates all “injustice” on the cross.

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[1] Tom Smail, Once for All: A Confession of the Cross (London, England: Darton, Longman, & Todd, 1998),  97; quoted in Steve Jeffery, Mike Ovey, and Andrew Sach, Pierced for Our Transgressions, 241.

[2] Jerry Bridges, The Gospel for Real Life (Colorado Springs, Co: NavPress, 2003, c2002), 37.

[3] John 15:1-7; 1 John 2:5-6; 2 Corinthians 5:17; Galatians 2:20; Ephesians 2:5-6; Colossians 3:1, among numerous other passages; John uses the term “in him” or “abiding” nearly 90 times and Paul uses the terms “in Christ”, “in Christ Jesus”, “in him”, “in the Lord” and similar expressions no less than 370 times according to Paige Patterson in A Theology for the Church, 688.

[4] Jeffery, Ovey and Sach, Pierced for Our Transgressions, 244.

[5] J. I. Packer, “Justification,” in Evangelical Dictionary of Theology, ed. Walter A. Elwell (Grand Rapids, MI: Baker, 1984), 596.