How do we know that imputation is a biblical doctrine?

The doctrine of imputation, as preached in Romans 4, illustrates how faith results in righteousness being attributed to the believer. Abraham's faith was imputed to him as righteousness before the law was given, demonstrating that righteousness is granted through faith, not works. This is further supported in Ephesians 2:8-9, where it states that we are saved by grace through faith, emphasizing that this faith is a divine gift. The Reformed understanding asserts that God imputes the righteousness of Christ to believers based on Christ's obedience, which qualifies them before God. This doctrine reinforces that salvation is entirely God's work, highlighting His justice and mercy.