“He made Him who knew no sin to be sin on our behalf, so that we might become the righteousness of God in Him.” 2 Corinthians 5:21 (NASB)
The pronouns in this verse should first be identified in order to grasp the meaning. The “one who knew no sin” is Jesus Christ. His sinless character is clearly affirmed in Scripture and supported by the Gospel accounts of His life.
At Calvary Jesus was made “to be sin on our behalf.” This is a reference to the substitutionary atonement, by which Jesus assumed the guilt of our sins and paid their penalty. This should not be read so as to imply that Jesus actually became a real sinner. He took the place of sinners, and He was punished as a sinner should be punished; but He will always be the one who in reality “knew no sin.”
The one who made all of this happen was God Himself. God was the “He” who made Jesus to be sin on our behalf. Once again we are reminded that Calvary was ultimately God’s plan, a program of redemption “foreknown before the foundation of the world” (1 Peter 1:20).
And never forget the other side of the substitution. Jesus took on the guilt of our sin so that “we might become the righteousness of God in Him.” We could never pass the judgment bar of God on the basis of our own record of good deeds; for no matter how much good we could show, it would never be enough to make up for our sins against God. That is why God’s grace allows us to assume Christ’s perfect record even as He assumes our guilt. True Believers stand before God fully reconciled to Him, not on the basis of their good deeds, but because He allows them to wear the righteousness of Christ.