For our sake he made him to be sin who knew no sin, so that in him we might become the righteousness of God. —2 Corinthians 5:21
John Piper asks, "How will you worship your Redeemer, if you do not know what he has done for you? How will you pursue righteousness, if you do not know the deepest obstacle?"
He says, "Christ has appeared once for all at the end of the ages to put away sin by the sacrifice of himself (Hebrews 9:26; 2 Corinthians 5:21). And when he died, all those who are his died with him and—united to him. We have been united with him in a death like his (Romans 6:5)."