J. I. Packer, in an article entitled, “Penal Substitution Revisited,” writes:

As I grow old, I want to tell everyone who will listen: ‘I am so thankful for the penal substitutionary death of Christ. No hope without it.’

Penal substitution is no mere corollary to the Gospel. It is the heart of the Gospel. And for a man who has served the Lord for all these years so humbly, graciously, and boldly to say such a statement is quite telling. And this one paragraph is such a strong summary of this most critical part of the Gospel:

Penal substitution, therefore, will not be focused properly till it is recognized that God’s redemptive love must not be conceived – misconceived, rather – as somehow triumphing and displacing God’s retributive justice, as if the Creator-Judge simply decided to let bygones be bygones. The measure of God’s holy love for us is that ‘while we were still sinners, Christ died for us’ and that ‘he…did not spare his own Son but gave him up for us all’ (Romans 5:8, 8:32). Evidently there was no alternative to paying that price if we were to be saved, so the Son, at the Father’s behest ‘through the eternal Spirit’ (Hebrews 9:14), paid it. Thus God ‘set aside…the record of debt that stood against us…nailing it to the cross’ (Colossians 2:14). Had we been among the watchers at Calvary, we should have seen, nailed to the cross, Pilate’s notice of Jesus’ alleged crime. But if, by faith, we look back to Calvary from where we now are, what we see is the list of our own unpaid debts of obedience to God, for which Christ paid the penalty in our place. Paul, having himself learned to do this, testified: ‘the life I now live in the flesh I live by faith in the Son of God, who loved me and gave himself for me’ (Galatians 2:20).

(HT: JT)