He took our Sin and having become Sin for us, is our Savior from Sin.
Therefore, if anyone is in Christ, he is a new creation. The old has passed away; behold, the new has come. All this is from God, who through Christ reconciled us to himself and gave us the ministry of reconciliation; that is, in Christ God was reconciling the world to himself, not counting their trespasses against them, and entrusting to us the message of reconciliation. Therefore, we are ambassadors for Christ, God making his appeal through us. We implore you on behalf of Christ, be reconciled to God. 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 Co 5:17–21.
from the ESV Study Bible note: This means that God the Father made Christ to be regarded and treated as “sin” even though Christ himself never sinned (Heb. 4:15; cf. Gal. 3:13). Further, we see that God did this for our sake—that is, God regarded and treated “our” sin (the sin of all who would believe in Christ) as if our sin belonged not to us but to Christ himself.
It is As If All your sins are not your sins, but it is as if Jesus committed them and not you. That is how God sees you. Like you have never sinned.
Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned … much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ.Therefore, as one trespass led to condemnation for all men, so one act of righteousness leads to justification and life for all men. 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. Romans 5: 12-19
How do we become God’s Righteousness?
In the beginning, God’s fellowship with humanity was unbroken, for each had within them the Holy Spirit: then the Lord God formed the man of dust from the ground and breathed into his nostrils the breath of life, and the man became a living being – Gen 2:7. Adam and Eve shared God’s Spirit and had perfect fellowship with the Father.
But Adam and Eve’s sin caused fellowship with God to be broken.
The LORD God took the man and put him in the garden of Eden to work it and keep it. And the LORD God commanded the man, saying, “You may surely eat of every tree of the garden, but of the tree of the knowledge of good and evil you shall not eat, for in the day that you eat of it you shall surely die.” Genesis 2:15–17
Adam’s body did begin to die after eating of the forbidden fruit, but his separation fin from God was immediate. His unbroken fellowship with God was gone.
For God is “too Holy to look upon sin.” He is too holy to fellowship with evil. He could not commune with Adam as he had done so before. Fear in Adam replaced love for God. In order for God to restore us to unbroken fellowship, he had to remove the barrier of sin and fear. The only way to do that was to experience death and pay the consequences of our sins.
Jesus had to die and be resurrected for us to receive God’s Holy Spirit anew. Before Jesus, no one, not even the most righteous had received an indwelling Holy Spirit. The Spirit rested upon the prophets, but did not indwell them. John quotes Jesus, and then offers an interpretation:
Whoever believes in me, as the Scripture has said, ‘Out of his heart will flow rivers of living water.’ ” Now this he said about the Spirit, whom those who believed in him were to receive, for as yet the Spirit had not been given, because Jesus was not yet glorified. John 7:38–39
Yet after he was raised something happened.
On the evening of that day, the first day of the week, the doors being locked where the disciples were for fear of the Judeans, Jesus came and stood among them and said to them, “Peace be with you.” When he had said this, he showed them his hands and his side. Then the disciples were glad when they saw the Lord. Jesus said to them again, “Peace be with you. As the Father has sent me, even so I am sending you.” And when he had said this, he breathed on them and said to them, “Receive the Holy Spirit.” John 20:19-23
Jesus gave back to us what Adam had lost… God’s Spirit.
He Who is Holy now lives inside you. You are Holy because he who lives in you is Holy. You have been made righteous by virtue of He who lives in you. Not in yourself, but in Him.
Therefore, guilt and condemnation over sin in your conscience is not from God, but a lie to keep you bound to sin, doubt, and feelings of separation from God. In short, to keep you from trusting Him, running to Him, from fellowship with Him.