Question: "What does it mean that Jesus became sin for us (2 Corinthians 5:21)?"
Answer: “God made him who had no sin to be sin for us, so that in him we might become the righteousness of God” (2 Corinthians 5:21). This verse has inspired a great deal of debate among theologians over the years. There is no doubt that the verse expresses a unique truth about Jesus: He became sin for us. While on the one hand the verse states the simple gospel truth that Jesus took upon Himself the sins of all who would ever believe in Him, it also makes a somewhat enigmatic statement. How exactly did God make Jesus to be sin for us?
Perhaps the best way to understand He became sin for us is to begin with what it does not mean. First, it does not mean that Jesus actually became sin itself. To posit such a theory denies all of Scripture, which clearly presents Jesus Christ as the One in whom there is no sin (1 John 3:5), who commits no sin (1 Peter 2:22), and who is holy, blameless, and pure (Mark 1:24; Acts 3:14; Revelation 3:7). For Jesus to “become” sin, even for a moment, would mean He ceased to be God. But Scripture presents Jesus as “the same yesterday, today and forever” (Hebrews 13:8). He was and is and always will be the Second Person of the Godhead (John 1:1).
Second, the idea that Jesus became sin for us does not mean that He became a sinner, not even for a moment. Some have said that Christ may be considered as the greatest of sinners, because all the sins of mankind (or at least of the elect) became His own sins. When Christ suffered in our place and died for us, He bore the punishment for our sins in His own body (1 Peter 2:24). But Jesus at no time became a sinner personally.
Third, it does not mean He was guilty of actual sin. No one is truly guilty who has not transgressed the law of God, which Jesus never did. If He were guilty, then He deserved to die, and His death could have no more merit than that of any other guilty person. Even the Pharisees who sent Jesus to Calvary knew He was guiltless: “And though they found in him no guilt worthy of death, they asked Pilate to have him executed” (Acts 13:28).
If He became sin for us does not mean Jesus was sin, or a sinner, or guilty of sin, the proper interpretation can only be found in the doctrine of imputation. This is confirmed by the second part of 2 Corinthians 5:21: “So that in him we might become the righteousness of God.” To impute something is to ascribe or attribute it to someone. On the cross, our sin was imputed to Christ. That is how Christ paid our sin debt to God. He had no sin in Himself, but our sin was imputed (attributed) to Him so, as He suffered, He took the just penalty that our sin deserves. At the same time, through faith, Christ’s righteousness is imputed to us. Now we can stand before God sinless, just as Jesus is sinless. We are not righteous in ourselves; rather, Christ’s righteousness is applied to us.
So, “God made him . . . to be sin for us” means that Jesus, although sinless, was treated as if He were not. Although He remained holy, He was regarded as guilty of all the sin in the world. Through imputation of our sin to Him, He became our substitute and the recipient of God’s judgment against sin. Having saved those who believe, He is now “our righteousness, holiness and redemption” (1 Corinthians 1:30).