“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
“Knew no sin” means mankind’s sins were charged to the account of an innocent man Jesus; who lived a perfect life, so He could be the final sacrifice in God’s plan of salvation for all mankind.
“To be sin” means Jesus took upon Himself our status and standing before God. He was declared guilty of ALL the sin and evil in this world. What an example of God’s love. Jesus never did anything wrong. Yet, He died for our sins, so that we could be declared righteous (justified) before God. The Greek word for righteousness has the same root term as “justify.” Christ’s righteousness, His “holy status,” was conferred and credited to those who believe in Him because of His death and resurrection. Paul is teaching us that Christ alone is our Righteousness when he says “the righteousness of God.“ We will one day stand in the presence of God Himself because of Jesus’ sacrifice for us! He is risen! He is risen indeed! Alleluia!