This excerpt is from the blog back in July 2006. Phil shows how a single verse encapsulates the Gospel message of our justification via Christ's substitutionary death.
Here is the apostle Paul's most succinct statement about the meaning of the cross. This could be the shortest, simplest verse among many in the Pauline epistles that make the meaning of justification inescapable: "He hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him."
That text is all about the atoning work of Christ. Its meaning can be summed up in a single principle: substitution. It describes an exchange that took place through the atonement that Christ offered—our sin for Christ's righteousness. He took the place of sinners so that they might stand in His place as a perfectly righteous man.
Notice the graphic language: He was made sin (that's the very epitome of all that is despicable and odious), so that we might be made righteousness (that's everything that is good and pure and acceptable in God's estimation). This was the exchange: our sin for His righteousness. Our sin charged to His account; His righteousness credited to our account. It is a profound concept, and several amazing things stand out on the face of this text.
First of all: The atonement was God's own sovereign plan and purpose. "He [God] hath made him [Christ] to be sin for us." It was God who appointed His own Son to stand in the place of sinners.
In the words of Acts 2:23, Christ was "delivered by the determinate counsel and foreknowledge of God." His death on the cross was not merely something inflicted on Him by the wicked hands of sinful men. This was not merely an atrocity instigated and carried out in the strength of human free will. God ordained it.
[...]
Second, this is pure grace: "He hath made him to be sin for us." Christ, who did not deserve the wages of sin, suffered the full weight of divine wrath on behalf of people who did not deserve anything but judgment. He did not deserve to die; we did not deserve to live; but He changed places with us.
[...]
Third, notice that what God planned and purposed was accomplished through the agency of the incarnate Christ—the eternal Son of God in human flesh, who did all this willingly, on our behalf. He "who knew no sin" became "sin for us."
Both His life and His death are in view here. The fact that He "knew no sin" speaks of His sinless life. The reality that "He [became] sin for us" speaks of His dying on the cross—when He stood in the place of sinners and bore the wages of their sin as if He Himself had been guilty of all of it.
And yet he wasn't. "[He] knew no sin." Again, that speaks of His perfect life. Born under the law, He fulfilled every jot and tittle of God's commandments perfectly, in every degree.
[...]
That message is what the true gospel is all about. No text of Scripture presents it more plainly or more concisely than this verse.