NOTES for Gal 3:15-29
Continuing his reflection on the Torah and on the promises given by God, Paul turns to legal analogies, comparing the promises given by God to Abraham and his descendants with an ordinary human will, which, once drawn up, cannot be changed by outsiders (v. 15). In speaking of a will, the apostle certainly had in mind the Kingdom which, in his view, was the subject of the will: after all, if it was promised both to Abraham and to his descendants, then the right to it belonged only to the one named in Abraham's will as heir. Paul, as can be seen, considers the Savior Himself the only lawful heir (v. 16). The apostle may have been following here a known rabbinic tradition according to which the Messiah appeared, in a certain sense, as the personified people of God.
In any case, Paul rightly held that the Torah, given as a law common to the whole people, could in no way cancel the concrete promises given by God, just as it could not cancel a concrete will which, according to the Torah, could not and must not be canceled by outsiders (vv. 17-18). Through this simple legal analogy Paul tries to bring home to his readers the fact that the Torah and the faithfulness that bound Abraham to God, and now binds Christians to Him, are different things. The Torah is needed until the coming of the Messiah, to whom what His followers now hope for had been promised (vv. 19-20). It is needed so that one will not stray from the path of righteousness while waiting for the Messiah.
If the Torah could in itself be a source of life, nothing more would be needed; but the Torah could not be such a source. It could only guard a person walking the path of righteousness, pointing out the danger of sin wherever that danger existed (vv. 21-23). Paul, of course, does not compare the Torah by chance to a pedagogue in the ancient or Hellenistic sense of the word: in those days a pedagogue was not a teacher or educator, but a servant, more often a slave and sometimes free, whose duties included taking a child to school and bringing him back so that he would not decide on the way to turn somewhere else instead of going to school (vv. 24-25). Indeed, the protective role of the Torah plainly loses its relevance in the Kingdom, where sin and evil are already behind us and the fullness of the life of the risen Christ unites into one all who have become its inhabitants and Abraham's spiritual heirs (vv. 26-28).