When does God impute righteousness to a believer?
God imputes righteousness to a believer at the moment of belief in the Gospel. When a person believes with the heart, not merely head knowledge, that Christ died for the world and for them, God immediately credits His righteousness to them, clothing them with the righteousness of Christ.
Les explains that righteousness is an imputed thing, not something earned. With the heart man believes unto righteousness, and as soon as we believe the Gospel, God imputes His righteousness. Les compares this to God clothing Adam and Eve with coats of skins, where the last part of the verse says He clothed them—meaning righteousness. He also points to Isaiah 61, where the speaker is clothed with the garments of righteousness, and to Romans chapter 3, where Paul says the same happens unto all that believe. Paul repeats that with the heart man believes unto righteousness, so God can actually clothe the believer with the righteousness of Christ.
For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation.