“Brothers, I draw an example from common human life”
Brothers, I draw an example from common human life: likewise, nobody annuls or adds a codicil to a covenant of a man, once it has been ratified. Now the promises were spoken to Abraham “and to his seed.” It does not say “and to his seeds,” as about many but about one: “and to your seed”—which is Christ. But this is what I mean: the Law which came 430 years later does not make void a covenant previously ratified by God, in order to nullify the promise. Hence, if the inheritance comes through Law, it no longer comes through the promise. However, by promise God has granted it to Abraham as a gift of grace.
In these verses, Paul sets up his opposition between physical descent and genealogy—which are equal to the literal, to Israel according to the flesh, which corresponds as well to the historical Jesus—and descent according to the promise, Israel according to the spirit, which corresponds to the risen Christ. N. T. Wright has recently contributed what I take to be a new and correct interpretation of this passage. “Seed” here does not mean Christ per se but rather “family,” as its Hebrew original often does as well. In order for the traditional Jewish theological conviction that in the end all will be saved through the covenant to be true, the promise must devolve on all in the end. Now it does not say “seeds,” families, but “seed,” family, so it follows that for the covenantal promise to come true, all of humanity must be constituted through Christ into a single seed (Wright 1992a, 162–68). The Law, which came later and serves a temporary function, could not be the means by which this will come about, since it divides humanity into families and does not join them into one seed. In any case, God's promise is a “gift of Grace,” a term which certainly echoes the Hebrew םניח תנתמ, where the Hebrew root for grace is used adverbially to mean a free, unconditional gift.