Archibald Alexander: Justification is grounded in the imputation of Christ's active and passive obedience

Archibald Alexander explains that Christ's preceptive and penal obedience alone are the basis for our pardon and acceptance with God:

When God imputes the righteousness of Christ to a sinner, he actually bestows it upon him for all the purposes of his complete justification. The sinner owes a righteousness to the law, which he cannot pay; but God in mercy reckons to him the perfect righteousness of another. For the sake then of Christ's satisfaction to the precept and penalty of the law he is pardoned and accepted as having a perfect righteousness in his Surety. (Archibald Alexander, A Treatise on Justification by Faith)