15 Brethren, I speak in the manner of men: Though it is only a man’s covenant, yet if it is confirmed, no one annuls or adds to it.
16 Now to Abraham and his Seed were the promises made. He does not say, “And to seeds,” as of many, but as of one, “And to your Seed,” who is Christ.
Brethren (v.15) — Paul switches from lecture to persuasion, but with the same passion.
manner of men (v.15) — according to the standards accepted by men
a man’s covenant (v.15) — Nobody would alter a human-made covenant once it was confirmed, but the Judaizers were altering the covenant made by God to Abraham — and claiming Divine authority to do so. The law did not replace or change the promise.
covenant (v.15) — here = gracious promise, determination of God to bless.
confirmed (v.15) — ratified
Seed (v.16) = Christ. The promise wasn’t to all Abraham’s seed, but only to those who believed, and therefore, were in Christ. So, to Christ and all who are in Him.
He does not say (v.16) — God didn’t say …
If the promise was Christ, and it was, the law couldn’t have annulled or altered it.
Perhaps it will help at this point first to notice what the verse does not say. It does not say that God would not bless Abraham’s multiplied seed, or through them the world. It does not say that God would bless only Christ, the single Seed, and make Him alone a blessing to the world, though in a sense this is true, for all blessing flows from Him. The apostle simply states that in making the promises to Abraham and his progeny, God used the word, “seed,” which is singular in form, and that He did this because He had Christ in view. In other words, God specially avoided the use of plural words which might have been used, such as “in thy children,” “in thy descendants,” etc., for there was no generation of Abraham’s offspring who, in themselves, could have proved a blessing to the world. — Studies in Galatians, Cornelius R. Stam, pages 182-183
Does it follow, then, that God’s promises concerning the multiplied seed will not be fulfilled because they forfeited the blessing through failure and unbelief, and that therefore the nations will be blessed through Christ alone?
Not exactly. Are we hedging when we answer the question in this way? No, for God will indeed bless the world through the multiplied seed of Abraham. This has been proven, not only by the uncomditional promises made to Abraham, Isaac, and Jacob, but also by repeated prophetic confirmations both before and after Pentecost. However, Israel will never become the world’s blesser until she does so through Christ because the blessing of the world is wrapped up on Him alone. — Studies in Galatians, Cornelius R. Stam, pages 184-185.
Thus Paul, in Galatians 3:16, does not mean to imply that god will not fulfill the promises to Abraham’s multiplied seed. He only points out that God used a compound or collective noun in making these promises since He knew that the multiplied seed could not in themselves prove a blessing to the world. It is redeemed Israel that will bless the world (Zechariah 8:13; Romans 11:26).
Thus, even the word “seed,” in Galatians 3:16, while singular in form (“Not many … but one”), is still plural in fact, for as we have said: we use the word “seed,” whether of one single seed or a a bagfull. Moreover, one seed contains much seed, potentially. This agrees with our Lord’s words in John 12:24:Most assuredly, I say to you, unless a grain of wheat falls into the ground and dies, it remains alone; but if it dies, it produces much grain. — Studies in Galatians, Cornelius R. Stam, pages 184-185.