Some people have what they refer to as “life verses”, or their favorite verse from the Bible. My favorite verse regarding doing my work for the Lord, for example, is Colossians 3:23: “Whatever you do, work heartily, as for the Lord and not for men.” My overall favorite verse in the Bible is 2 Corinthians 5:21: “For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God.” This verse is a description of the gospel.  Chris Tomlin summarized this in the opening lines of his song “Jesus Messiah”:

He became sin, who knew no sin
That we might become his righteousness

The great reformer Martin Luther called what is described in 2 Corinthians 5:21 “the great exchange”. Christ took on himself the punishment of our sin, and in exchange, God reckoned to our account the perfect righteousness of his son. Talk about good news!
Luther stated:
“That is the mystery which is rich in divine grace to sinners: wherein by a wonderful exchange our sins are no longer ours but Christ’s and the righteousness of Christ not Christ’s but ours. He has emptied Himself of His righteousness that He might clothe us with it, and fill us with it. And He has taken our evils upon Himself that He might deliver us from them… in the same manner as He grieved and suffered in our sins, and was confounded, in the same manner we rejoice and glory in His righteousness.”
The ESV Study Bible states that this is one of the most important verses in all of scripture for understanding the meaning of the atonement and justification.  This verse shows that Christ became our substitute, bearing the wrath and judgment of God in our place, and accepting the penalty of sin in our place. Just as God imputed (treated as if it were ours through faith) our sin and guilt to Christ, God also imputes the righteousness of Christ to all who believe in Christ.
John MacArthur tells us in the MacArthur Study Bible, that Paul summarizes the heart of the gospel in this verse. He states that on the cross Jesus was treated as if he were guilty of all the sins ever committed by all who would ever believe, though he committed none. The wrath of God was exhausted on Jesus and the just requirement of God’s law met for those for whom he died. Jesus bore our sins that that we could bear his righteousness.
As Pastor Scott Sauls says, “on the cross, Jesus took the punishment that our sins deserve, thereby moving our judgment day from the future to the past. In Jesus, we are already completely forgiven, so we have nothing left to fear.” This is an incredible truth. What does it mean to you that Jesus took on your sin and in return you were able to take on his righteousness?