Charles Ellicott Commentary Galatians 3:15

"Brethren, I speak after the manner of men: Though it be but a man`s covenant, yet when it hath been confirmed, no one maketh it void, or addeth thereto." — Galatians 3:15 (ASV)

I speak after the manner of men.—The figure I am going to use is taken from ordinary civil relations between individuals. It is therefore to be inferred that this supplies an à fortiori argument in matters relating to God. For humans may change and break the most solemn engagements, whereas God is absolutely faithful and unchangeable. The phrase translated “I speak after the manner of men” is found in the same, or a very similar form, in Romans 3:5, Romans 6:19, and 1 Corinthians 9:8; see the Notes on these verses.

Though it be but a man’s covenant.—This is well rendered in the Authorized Version. A covenant, even though it is only between two individuals—though it is regulated only by the provisions of human law—does not admit of alteration or addition after it has once been signed and sealed; how much more so a covenant that depends on God.

Covenant.—The word translated this way is the one that gave its name to the “Old and New Testaments,” where a more correct rendering would be the “Old and New Covenants.” The word has both senses. It originally meant a “disposition” or “settlement,” and hence it came, on the one hand, to be confined to a “testamentary disposition,” while, on the other hand, it was taken to mean a settlement arrived at by agreement between two parties. The first sense is the one most commonly found in classical writers; the second is used almost entirely in the LXX and New Testament. The one exception is in Hebrews 9:15-17, where the idea of “covenant” glides into that of “testament,” the argument turning rather on the double meaning of the word.

Addeth thereto.—This means to add new clauses or conditions. Such new clauses could only be added by a second covenant. The reason the Apostle introduces this point is that the Law might be supposed to restrict the scope of the promise. It might be thought to add certain new and limiting conditions, compliance with which was necessary for the blessings of the promise to be obtained. This was the position of the Judaizing party, against which Saint Paul is arguing.

On verses 15-18:

To take an illustration from purely human relations: a covenant, once ratified, is binding. It cannot be treated as if it did not exist, nor can fresh clauses be added to it.

Now, the covenant and promise made to Abraham (by the terms in which it was made) could point to no one but the Messiah. That covenant remained unaffected by the Law, which came four hundred and thirty years later.

Law and promise are two totally different and mutually exclusive things. The covenant with Abraham, however, was given by promise. The Law, therefore, had nothing to do with it.