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 Cor 5:21
In the above verse the word sin, is a noun, not a verb. In fact much of the time we see sin in the New Testament, it is a noun. In Romans for example, 47 out of 49 times the word sin is a noun. We all know that a noun is a person, place or thing and not an action. Therefore, this verse, like the ones in Romans is not talking about our individual acts of sin. It is speaking of the sin nature we inherited from Adam that is made apparent by its symptoms, our individual acts of sin.
Realizing sin is a noun in 2 Cor 5:21, we understand this verse is telling us that Jesus literally became our inherited sin nature, crucifying it on the cross.
Now for even better news. The word “righteousness” in this verse is a noun also. In other words, this verse is saying Jesus literally became our sin nature and we literally became His righteous nature upon belief.
We know Jesus is righteous, right with the Father, and because He is, we also are “…as he (Jesus) is so also are we in this world.”1 John 4:17b
But now the righteousness of God has been manifested apart from the law, although the Law and the Prophets bear witness to it – the righteousness of God through faith in Jesus Christ for all who believe… Rom 3:21-22 ESV
Here Romans makes it abundantly clear how we were made sinners and how a person can be made righteous.
For as by the one man’s disobedience the many were made sinners, so by the one man’s obedience the many will be made righteous,Rom 5:19.