Why is it important to understand penal substitutionary atonement?

MACARTHUR: If you don’t understand the doctrine of penal substitution, you don’t know why Christ died. You would assume that if you’re a Christian, you would want to know why Christ died.

In 2 Corinthians 5:18–21, Paul says that we are ambassadors. We go into the world and beg people to be reconciled to God. He’s given us the Word of reconciliation. That’s the message we preach: “You can be reconciled to God.” We have the ministry of reconciliation and the message of reconciliation. But how is it possible for a sinner to be reconciled to a holy God? That is the most legitimate question a sinner could ever ask: “If God is holy, righteous, and perfect, how is it possible for me to be reconciled to a holy God without Him tarnishing His holiness?” To put it in the language of Paul, How can God be “just and the justifier” of sinners? (Rom. 3:26). That is the absolute apex question of all religion.

The primary question that religion attempts to answer, whatever god a religion espouses, is: “How can I go from being God’s enemy to being His friend? How can I make peace with God?” All religion is designed to somehow come to terms with the deity. In Christianity, the question is built around holiness, justice, and righteousness: “How can God forgive me and still be holy?” The only thing that answers that question is penal substitution.

Penal substitution says God is so holy that every sin will be punished. Every single sin in the life of every Christian believer through all of human history was punished. All sin must be punished. Either the sinner will bear that punishment eternally, or Christ took that punishment on the cross. The only thing that protects the pure, righteous holiness of God is that sin is punished. That’s penal substitution. If you remove that part of the cross, then how does God reconcile His holiness with wishing sin away without a punishment? There has to be a punishment for God to maintain His justice. That punishment falls on His Son.

BINGHAM: I can remember before I became a Christian, but at a time when I had heard the gospel a number of times, sitting down with the woman who is now my wife and asking her: “Explain to me John 3:16. Why did God have to send His Son? Why did Jesus have to die? Why didn’t God bake brownies to save the world? What’s this whole dying on the cross thing?” At the time, she couldn’t answer the question. We had to go into church and try to get information about penal substitution because all the gospel presentations I’d heard were missing that phrase.

MACARTHUR: You see, that is the question. Penal substitution is not some kind of optional issue. You’ve got a massive problem if God just says, “Hey, you’re forgiven.” The character of God would be called into question as to His integrity, His holiness, His virtue, His righteousness, and His perfection. God is so pure and holy that He will punish every single sin ever committed by every person, either in that person or in the substitute for that person. That is the purest heart of Christianity and soteriology.