Imputed righteousness is the heart of the Reformation doctrine of justification by faith alone. The word "imputed" (Greek logizomai) is a legal and bookkeeping term: it means to credit something to someone's account. Abraham "believed God, and it was accounted [imputed] to him for righteousness" (Romans 4:3, citing Genesis 15:6). Abraham was not righteous in himself; his righteousness was a gift credited to his account by faith. Paul expands this in 2 Corinthians 5:21: "For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him." There is a double imputation at the cross: our sin is imputed to Christ, and His righteousness is imputed to us. This is not a legal fiction but a legal reality — God really declares the believing sinner righteous, not because the sinner has earned it, but because Christ has earned it and God has joined the sinner to Christ by faith. The Roman Catholic doctrine of infused righteousness teaches that God makes us righteous gradually through the sacraments; the Protestant doctrine of imputed righteousness teaches that God declares us righteous instantly through faith, and then makes us actually righteous through progressive sanctification. The order matters. Justification precedes sanctification; imputation precedes infusion.