Charles H. Spurgeon testified, "My hope lives not because I am not a sinner, but because I am a sinner for whom Christ died; my trust is not that I am holy, but that being unholy, HE is my righteousness."
By faith in the Lord Jesus Christ, believers receive the gift of God's perfect righteousness. When we believe on the name of the Lord Jesus Christ, we "become the righteousness of God in Him" (2 Corinthians 5:21). That is the imputed righteousness of God in Christ, accounted to every believer.
"But we are all like an unclean thing, and all our righteousness is like filthy rags" (Isaiah 64:6). We receive the imputed righteousness of God in Christ. It is the gift of God received by faith in the Lord Jesus Christ. Believers are accounted righteous by God in Christ alone.
How did Abraham become righteous? He was righteous by faith in the Lord. He received God's imputed righteousness by faith. Abraham is our example three times in the New Testament on how to receive God's righteousness (Romans 4:3; Galatians 3:6; James 2:23)."And he believed in the Lord, and He accounted it to him for righteousness" (Genesis 15:6).
