I suggest that we as Lutheran pastors rethink the Law / Gospel dialectic as we learned it from the Formula of Concord, Walther and Pieper.

What two items are being contrasted in Gal. 3:23ff? (see my translation below)

Is it faith v. the Decalogue? Which in turn is usually (and wrongly) understood as redemption by mental activity v. redemption by good behavior?

Or said another way: salvation by affirming certain scriptural propositions v. salvation by doing good works?

Or said yet another way: justification before God by thinking something v. doing something?

(By mindset v. behavior?)

The Reformed (today's Evangelicals) took this to its logical conclusion and thereby denied the power of baptism because baptism, in their (wrong) understanding is something someone "does" but St. Paul says, that men are "justified by faith," that is by what they think. By mindset, not behavior.

What St. Paul contrasts here, I believe, is salvation by the OT sacrificial system v. salvation by Christ. When he says in v. 24 "in order that we might be justified by faith" what he means is: in order that we might be justified by the Christ event.
If this is so then in v. 25 we could say this: But now that Christ has come, we are no longer under Torah / the OT sacrificial system.

As often as we hear St. Paul contrast "nomos" (law) with "pistis" (faith) we should not think of "nomos" as the Decalogue but as Torah. As the OT sacrificial system, as "the blood of beasts on Jewish altars slain" (LSB #431) by which sins were forgiven, and salvation obtained.

Moreover we should not think of "pistis" as mental activity but as the entire Christ event and our sacramental participation in it.

Faith is not opposed to works, indeed Christ redeemed us so that we might "show forth the praises of him who called us out of darkness into his marvelous light." (1 Peter 2) To set up a prize fight between these two, between faith and Christian behavior is to lose one's way.

Galatians 3:23ff (DKV)

23 Now before the advent of faith we were held captive,
locked up until the coming faith should be unveiled.

24 So then Torah was made to be our guardian until Christ,
that we might be made just by faith.

25 But with the coming of faith we are no longer under a guardian
26 for we are all sons of God through faith in Christ Jesus.

27 For as many as are baptized INTO Christ
have clothed themselves with Christ.

28 In Christ there is neither Jew nor Greek;
in Christ there is neither slave nor free;
in Christ there is neither male nor female;
for you are all one in Christ Jesus.

29 And if you are Christ's, then you are offspring of Abraham,
heirs in accord with the promise.