Why our own record cannot save us
The question begins with the Bible's serious view of sin. Paul says all people have fallen short of God's glory, and that works of the law cannot justify anyone before him (Romans 3:20, Romans 3:23). Even sincere obedience cannot erase the wrong we have done or put us in God's debt.
This does not mean human goodness is worthless. It means goodness cannot be the foundation of our acceptance with a holy God. We need mercy. We need God to do for us what we cannot do for ourselves.
For all have sinned, and come short of the glory of God;
What imputed righteousness means
Imputed righteousness is a Protestant, particularly Reformed, way of explaining justification, God's verdict that a sinner is right with him. To impute means to credit or reckon to someone's account. Paul uses this kind of counting language when he says Abraham's faith was counted for righteousness (Romans 4:3).
In this view, believers are not accepted because faith itself is a meritorious achievement. They are united to Christ by faith, their sin is dealt with through his death, and his righteous standing is credited to them. Protestants often see this exchange expressed in 2 Corinthians 5:21: Christ, who knew no sin, bears sin's burden so that those in him receive righteousness from God.
So God is not simply overlooking evil or pretending people are already morally perfect. The cross shows both God's judgement of sin and his costly grace towards sinners.
For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.
Christians do not all frame it the same way
Catholic, Orthodox, and some other Christians do not usually make the imputation of Christ's personal righteousness the central explanation of justification. They also confess that nobody saves themselves and that salvation comes through Christ alone. Yet they often stress that God's grace truly renews a person, heals sin, and enables a real participation in Christ's life.
The New Testament gives language that Christians across these traditions value. Paul contrasts his own righteousness with the righteousness that comes from God through faith in Christ (Philippians 3:9). He also says that those in Christ become a new creation (2 Corinthians 5:17). The traditions differ over how these truths fit together, but none should turn grace into a reward for spiritual performance.
Grace leads to a changed life
Receiving Christ is not a licence to be careless with sin. Paul says those joined to Christ are called to walk in newness of life (Romans 6:4). Good works matter because God is changing his people, not because they purchase a place in his family.
If the word imputed feels technical, hold on to the heart of it: come to God with empty hands, not a résumé. Trust Jesus rather than your ability to prove yourself worthy. Then keep reading the Gospels and Paul's letters, asking God to form Christ's love and faithfulness in you.
Therefore we are buried with him by baptism into death: that like as Christ was raised up from the dead by the glory of the Father, even so we also should walk in newness of life.