Sam Storms on JI Packer on Penal Substitution:
In the on-going debate about the nature of Christ’s atoning death, some have insisted that penal substitution is only one model among many others. My contention has always been that it is more than one of many models and is in fact the central and controlling foundation for everything the atonement accomplished on behalf of sinners. Without it, there is no gospel and there is no salvation. I was pleased to come across this statement by J. I. Packer in which he affirms precisely the same point.
Packer proceeds to explain how penal substitution theologically explains everything else regarding the saving efficacy of Christ’s death. Note the following sequence.
“What did Christ’s death accomplish? It redeemed us to God – purchased us at a price, that is, from captivity to sin for the freedom of life with God (Tit 2:14; Rev 5:9). How did it do that? By being a blood-sacrifice for our sins (Eph 1:7; Heb 9:11-15). How did that sacrifice have its redemptive effect? By making peace, achieving reconciliation, and so ending enmity between God and ourselves (Rom 5:10; 2 Cor 5:18-20; Eph 2:13-16; Col 1:19-20). How did Christ’s death make peace? By being a propitiation, an offering appointed by God himself to dissolve his judicial wrath against us by removing our sins from his sight (Rom 3:25; Heb 2:17; 1 Jn 2:2; 4:10). How did the Savior’s self-sacrifice have this propitiatory effect? By being a vicarious enduring of the retribution declared due to us by God’s own law (Gal 3:13; Col 2:13-14) – in other words, by penal substitution” (416, "The Atonement in the Life of the Christian").
The inescapable fact is that if Christ’s death was not of the nature of a penal substitutionary sacrifice, we simply have nothing in the way of good news to share with a lost and dying world.