The Protestant doctrine affirms that a sinner is made or constituted righteous by having Christ’s righteousness imputed to him; and that, being thus justified actually, he is also justified declaratively, when his acceptance is proved or attested, so as to be made manifest to his own conscience, or to his fellow-men. In both cases it is one and the same Justification that is spoken of,—his acceptance as righteous in the sight of God; but, in the one, it is considered simply as a fact, in the other, as a fact that is attested and proved. Actual Justification comes first, and is necessarily presupposed in that which is declarative; and hence, if any one is declared to have been justified, we conclude that he was actually justified, or accepted as righteous in the sight of God.

…And on that solemn occasion, just as in the case of the woman that was a sinner, the acquittal and acceptance of the believer will not only be authoritatively declared by the sentence of the Judge, but that sentence will refer to the fruits of his faith, and especially to his love to Christ, as manifested by love to His afflicted people: ‘Inasmuch as ye did it to one of these my brethren, ye did it unto me.’ Justification, considered as the pardon of a sinner and his acceptance as righteous in the sight of God, is by faith; but judgment is according to works; and it is not a second Justification,—as if there might be two—the one by faith, the other by works—it is one and the same Justification, which is actually bestowed in the present life, and authoritatively declared and attested at the judgment-seat.

…From the age of Augustine downwards, the most various and conflicting interpretations have been proposed. Recourse has been had to each of the principal terms in succession,—Justification,—Faith,—Works,—with the view of finding, in one or other of them, a means of harmonizing the teaching of the two Apostles. Some have founded their theory on the first of these terms, and have contended for a first and second, or an initial and final, Justification,—not in the sense of the one being actual, and the other declarative merely,—but in the sense of both being actual, while the one is by faith, and the other by works. Others have founded on the second term, and have attempted to show that, if every believer is actually justified in the present life, it can only be because faith is considered as the germ of personal holiness, and as comprehensive of all the other graces, and acts of new obedience, which spring from it. Others still have founded on the third term, and have endeavoured to show, that the works which are excluded from the ground of our Justification, are—either mere ceremonial observances such as were enjoined in that part of the Mosaic law which is now abolished,—or moral duties such as the heathen practised, which were done in the unaided strength of nature, without grace, and before faith in Christ,—or perfect obedience to the divine law, such as no man in his own strength can possibly accomplish, but not that sincere, though imperfect, obedience which every Christian is enabled by the grace of the Spirit to render to its requirements.

…Paul, in his Epistles to the Romans and Galatians, treats at great length, and with much earnestness, the question of a sinner’s actual Justification, or acceptance in the sight of God. He states the conclusion of his whole argument, when he says, ‘Therefore by the deeds of the law shall no flesh be justified in His sight: for by the law is the knowledge of sin;’ and again, ‘Therefore we conclude that a man is justified by faith, without the deeds of the law.’ …So that man’s righteousness arising from his works of obedience to the divine Law, is excluded from the ground of his Justification on two distinct grounds,—first, on the ground of God’s Law, which convicts and condemns every sinner;—and secondly, on the ground of God’s method of redeeming mercy, which brings in another righteousness altogether,—the righteousness of Him who ‘became obedient unto death, even the death of the Cross.’ It is manifest from the whole course of his argument, that Paul’s design was to explain the method and ground, and even, to some extent, the rationale, of the actual justification of a sinner in the sight of God,—to show how, and why, he may be forgiven and accepted as righteous,—and to set forth this as the immediate privilege of every believer, as soon as he renounces all confidence in his own righteousness, and submits ‘to the righteousness of God.’

…It is equally clear, that the Apostle James, while he refers incidentally, or by necessary implication, to the actual justification of sinners in the sight of God, is not engaged in expounding either the nature, or grounds, of that great Gospel privilege, but rather in illustrating the declarative justification of believers, or the practical evidence by which their actual justification is attested and proved. He refers to the same justification of a sinner in the sight of God, which is more fully expounded by Paul; for he speaks, like Paul, of the justification of Abraham, which was evidently, in the first instance, that of a sinner before God; and for this reason, it is a defective statement to say that he speaks only of justification before men. But actual justification is necessarily presupposed in that which is declarative; for the latter is the mere evidence, manifestation, or proof of the former; and the Apostle proves the actual justification of Abraham, first, from the testimony of God Himself, as it is recorded in Scripture, ‘which saith, Abraham believed in God, and it was imputed unto him for righteousness: and he was called the Friend of God;’ and secondly, from the practical fruits or manifestations of his faith in works of holy obedience: ‘For was not Abraham our father justified by works, when he had offered Isaac his son upon the altar?’

—James Buchanan, The Doctrine of Justification: An Outline of Its History in the Church and of Its Exposition from Scripture.(Edinburgh: T&T Clark, 1867), 234, 238, 239–40, 241, 243–44.