But God didn’t stop there with reconciling Himself to us; He goes on to tell us to also be reconciled to Him! That means to quit trying to pay back that debt that He already paid. Remember, on the cross He shouted out that "It is finished!" The debt was paid in full on that day.
And he has committed to us the message of reconciliation. We are therefore Christ's ambassadors, as though God were making his appeal through us. We implore you on Christ's behalf: Be reconciled to God. (2 Corinthians 5:19-20)
He took on all of our sin --became sin-- for us so that we can have the righteousness of God.
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)
Nearly every time that reconciliation is discussed, the questions is raised "If the whole world is reconciled to God, then isn’t everyone saved?" The last part of the passage states "so that in Him we might become the righteousness of God." It’s conditional. To have God’s righteousness, we must be in Christ --saved. Christ is righteous. Being in Him --clothed in Christ-- is what makes us righteous.
Therefore, if anyone is in Christ, he is a new creation; the old has gone, the new has come! All this is from God, who reconciled us to himself through Christ and gave us the ministry of reconciliation: that God was reconciling the world to himself in Christ, not counting men's sins against them. (2 Corinthians 5:17-19)
Have you quit trying to pay Him back for what He has done? In other words, are you reconciled to God? He made peace with you and will never bring your sins up (that's what He said in 2 Corinthians 5:19). That means that there is nothing that you must achieve to be good in His eyes. If you're in Christ, then you are righteous!