Commentaries
3:15-18 The covenant God made with Abraham, was not done away by the giving the law to Moses. The covenant was made with Abraham and his Seed. It is still in force; Christ abideth for ever in his person, and his spiritual seed, who are his by faith. By this we learn the difference between the promises of the law and those of the gospel. The promises of the law are made to the person of every man; the promises of the gospel are first made to Christ, then by him to those who are by faith ingrafted into Christ. Rightly to divide the word of truth, a great difference must be put between the promise and the law, as to the inward affections, and the whole practice of life. When the promise is mingled with the law, it is made nothing but the law. Let Christ be always before our eyes, as a sure argument for the defence of faith, against dependence on human righteousness.
15. I speak after the manner of men—I take an illustration from a merely human transaction of everyday occurrence.
but a man's covenant—whose purpose it is far less important to maintain.
if it be confirmed—when once it hath been ratified.
no man disannulleth—"none setteth aside," not even the author himself, much less any second party. None does so who acts in common equity. Much less would the righteous God do so. The law is here, by personification, regarded as a second person, distinct from, and subsequent to, the promise of God. The promise is everlasting, and more peculiarly belongs to God. The law is regarded as something extraneous, afterwards introduced, exceptional and temporary (Ga 3:17-19, 21-24).
addeth—None addeth new conditions "making" the covenant "of none effect" (Ga 3:17). So legal Judaism could make no alteration in the fundamental relation between God and man, already established by the promises to Abraham; it could not add as a new condition the observance of the law, in which case the fulfilment of the promise would be attached to a condition impossible for man to perform. The "covenant" here is one of free grace, a promise afterwards carried into effect in the Gospel.