I speak after the manner of men - I am about to produce an example taken from civil transactions. If it be confirmed - If an agreement or bond be signed, sealed, and witnessed, and, in this country, being first duly stamped;
No man disannulleth - It stands under the protection of the civil law, and nothing can be legally erased or added.
Brethren, I speak after the manner of men - I draw an illustration from what actually occurs among people. The illustration is, that when a contract or agreement is made by people involving obligations and promises, no one can add to it or take from it. It will remain as it was originally made. So with God. He made a solemn promise to Abraham. That promise pertained to his posterity. The blessing was connected with that promise, and it was of the nature of a compact with Abraham. But if so, then this could not be effected by the Law which was four hundred years after, and the Law must have been given to secure some different object from that designed by the promise made to Abraham, Galatians 3:19. But the promise made to Abraham was designed to secure the “inheritance,” or the favor of God; and if so, then the same thing could not be secured by the observance of the Law, since there could not be two ways so unlike each other of obtaining the same thing.
God cannot have two ways of justifying and saving people; and if he revealed a mode to Abraham, and that mode was by faith, then it could not be by the observance of the Law which was given so long after. The main design of the argument and the illustration here (Galatians 3:15 ff) is to show that the promise made to Abraham was by no means made void by the giving of the Law. The Law had another design, which did not interfere with the promise made to Abraham. That stood on its own merits, irrespective of the demands and the design of the Law. It is possible, as Rosenmuller suggests, that Paul may have had his eye on an objection to his view. The objection may have been that there were important acts of legislation which succeeded the promise made to Abraham, and that that promise must have been superseded by the giving of the Law. To this he replies that the Mosaic law given at a late period could not take away or nullify a solemn promise made to Abraham, but that it was intended for a different purpose.
Though it be but a man‘s covenant - A compact or agreement between man and man. Even in such a case no one can add to it or take from it. The argument here is, that such a covenant or agreement must be much less important than a promise made by God. But even that could not be annulled. How much less, therefore, could a covenant made by God be treated as if it were vain. The word “covenant” here ( διαθήκη diathēkē) is in the margin rendered “Testament;” that is, will. So Tyndale renders it. Its proper Classical signification is will or testament, though in the Septuagint and in the New Testament it is the word which is used to denote a covenant or compact; see the note at Acts 3:25. Here it is used in the proper sense of the word covenant, or compact; a mutual agreement between man and man. The idea is, that where such a covenant exists; where the faith of a man is solemnly pledged in this manner, no change can be made in the agreement. It is ratified, and firm, and final. “If it be confirmed.” By a seal or otherwise.
No man disannulleth - It must stand. No one can change it. No new conditions can be annexed; nor can there be any drawing back from its terms. It binds the parties to a faithful fulfillment of all the conditions. This is well understood among people; and the apostle says that the same thing must take place in regard to God.