In some places, Scripture teaches also a justification on the basis of works1, namely, the justification before men. When we speak of justification in this signification, we use the term in a wider sense. The true justification, which is before God (ἐνώπιον ϑεοῦ) and by which a sinner becomes a child of God, is by faith, without the deeds of the Law, Rom. 3, 20—22. However, such faith is known only to God; before men it remains invisible. For this reason God justifies His believing saints before men by their works; that is to say, He proves their faith and justification by their fruits, Luke 7, 47; John 13, 35; Matt. 12, 37; 25, 34—40. So also all Christians should recognize their state of grace by the fruits which the Holy Spirit has wrought in their hearts, 1 John 3, 14; 2, 3.4; 2 Pet. 1, 10; Matt. 6, 14.
The Apology remarks very correctly Art. III, 154:
“Christ often connects the promise of the remission of sins with good works, not because He means that good works are a propitiation, for they follow reconciliation; but for two reasons. One is, because good fruits must necessarily follow. Therefore He reminds us that, if good fruits do not follow, the repentance is hypocritical and feigned. The other reason is, because we have need of external signs of so great a promise, because a conscience full of fear has need of manifold consolation. As therefore Baptism and the Lord’s Supper are signs that continually admonish, cheer, and encourage desponding minds to believe the more firmly that their sins are forgiven, so the same promise is written and portrayed in good works in order that these works may admonish us to believe the more firmly.”
The justification on the ground of works thus coincides with the external testimony of the Holy Ghost (testimonium externum sive indirectum), which we distinguish from His internal testimony (testimonium internum sive directum), or faith.
However, justification by faith and justification by works must not be mingled together, Gal. 3, 10. By the former the sinner obtains salvation; by the latter he is proved an heir of salvation. In order to make this matter clear, Luther sometimes speaks of inward and outward forgiveness. By the former he means justification before God; by the latter, justification before men. By the former a sinner becomes a child of God; by the latter he is proved a child of God. It is the basic error of Romanism to regard justification by works as the ground of a sinner’s justification and thus to make salvation depend on good works.
It is evident that the doctrine of justification by faith (sola fide) cannot be taught in its purity unless the Scriptural distinction between the Law and the Gospel is observed. The Law must never be mingled with justification, since this gracious act of God belongs entirely in the Gospel. But the Law is mingled with justification whenever the latter is based, either in whole or in part, upon some natural or spiritual virtue in man or when faith is said to justify as a “good quality” or as the source of sanctification or as compliance with the demands of the Law or as the beginning of the Christian’s new life, etc. In short, the Law is mingled with justification whenever justification is grounded, in whole or in part, on human works (Pelagians, synergists, Arminians).
Such mingling of the Law with justification destroys, of course, the blessed consolation which God has intended to bestow upon men by the glorious doctrine of justification by faith. While the doctrine of justification by faith gives the believer full assurance of salvation, that of justification by works removes this assurance; for it takes salvation out of the gracious hand of God and places it in man’s own sinful and impotent hand. It is a significant fact that all errorists who deny the sola fide deny also the Scriptural truth that a believer may be sure of his salvation.
Foremost among these errorists is the Pope, whom Luther exposed as the Antichrist, showing him to be such not because of his unholy works, but mainly because of his shameful perversion of the Scriptural doctrine of salvation by grace through faith in Christ. Luther’s assertion as to the Pope’s being the Antichrist spoken of in 2 Thess. 2 is correct; for to this day the anathema of the Council of Trent upon all true Christians who adhere to the Scriptural doctrine of justification by faith is upheld by the Church of Rome.