See part I here.
Even as they are not to be mixed or confused, faith and the Law are meant to complement one another, to go hand in hand, from Old to New Testament, from first to last. Even as the Law was always there in part to lead us to our need for God’s mercy (mercy found in circumcision, the daily sacrifices, and any other “means of grace” that also pointed to the Lamb of God who would come, or later on, those New Testament sacraments given by the Lamb in the flesh) we were to live by the Law in the right sense – perhaps more “in” the Law, as the Lutheran Formula of Concord says. But we were not meant to live by it in the sense of doing over receiving en route to justifying ourselves.
But the flesh can never understand this.
So Paul is right – all those who rely on works of the law are under a curse (again, note that Paul’s opponents in Galatia did not see that circumcision was actually a means of grace to be passively received and point to Christ [see Rom. 4:11,13,16], but made it like the other Laws we are to do, therefore Paul treated them accordingly, associating circumcision not with the Promise [see Gen. 17:10] – which would be correct – but with Sinai!). The Law cannot be understood apart from understanding the merciful person who speaks the Law.
In the 4th century, the Church father Athanasius successfully countered the Arian heresy. At one point in his writings vs. Arius, he talks about how a baptism is not valid unless those who speak the Name of the “Father, Son, and Spirit” utter it with the correct understanding.
I believe we in the Lutheran Church would say a tentative “yes” to this. Surely, insofar as we are talking about having a true Church, the meaning of the words must be the same for God’s people and God Himself (even if God can certainly can make His Words mean what they really do when and where He pleases – and can create true faith even through these). Athanasius’ point is well taken: God’s true people are those who properly understand the meaning behind the words given.
And Paul, not the Judaizers, had the proper understanding of the words and hence, of the One who spoke them. The Law cannot be properly understood without knowing and understanding the Person behind it – the One who incarnates both the Law and the Gospel. And when this happens, Augustine is right: “love God and do what you will”, for the believer will always readily recognize God’s Law, even as he needs “no one to teach him” (i.e. formally inculcate).
In the end, theology really is a non-theoretical exercise, just like understanding a Person is a non-theoretical enterprise. We understand someone not because we have a better theory (causation), but because we know a Person (hat tip to the philosopher Ray Monk)
If we know a person well, we know why they do what they do, even if others are puzzled. We can present and describe a way of seeing someone so that another may be able to say “oh, now they make sense”.
I hope all of this makes sense.