15 Brothers and sisters, let me take an example from everyday life. Just as no one can set aside or add to a human covenant that has been duly established, so it is in this case. 16 The promises were spoken to Abraham and to his seed. Scripture does not say “and to seeds,” meaning many people, but “and to your seed,”[i] meaning one person, who is Christ.17 What I mean is this: The law, introduced 430 years later, does not set aside the covenant previously established by God and thus do away with the promise. 18 For if the inheritance depends on the law, then it no longer depends on the promise; but God in his grace gave it to Abraham through a promise.
Some people talk about the ‘Abrahamic ecumenism’. There are differences between Judaism, Christianity and Islam. The idea is that if everyone will keep their specialities to themselves we are all one family and share in Abraham’s blessing.
Paul writes that when God made a covenant with Abraham and his offspring, he only had one descendant in mind: Christ. The Greek word ‘sperma’, is translated with ‘seed’ here. However, it can also indicate “offspring” (Rom. 4:13). Paul is playing with the word ‘seed’: taken as plural, this word does point at a big ‘bunch’ of children. Taken as singular, it refers back to the moment when God came to Abraham, where He came with the gospel of Christ. Thanks to HIM God’s promises from Genesis 17 would become truth: the children, grandchildren and great-grandchildren of the archfather will be heirs of the world (Rom. 4:13).
“Brothers and sisters”, the apostle says. The Galatians could stay within the family if God’s promise would have priority over the law. Not because Jesus had replaced the law, but because the promise came before the law, almost half a millennium. Never did laws replace the sola gratia, grace alone. God gave them to bring people into Christ’s arms. God keeps his word: salvation exists through faith alone. The oldest covenant remained valid. It has more power than any lawful interpersonal contract.
His covenant he remembered hath,
that it may ever stand:
To thousend generations
the word he did command.
Which covenant he firmly made
with faithful Abraham
And unto Isaac, by his oath,
he did renew the same.