I'm still trying to get a handle on this third use thing.
Me, too.
I agree that trying to derive law out of Gospel destroys the Gospel (I also think it is a mis-use of the Law). Isn't telling one another "you should" or "you shouldn't" because you have been redeemed a matter of deriving law out of the Gospel if such conversations are rationalized on the basis of 3rd use? Please understand that I am not suggesting that such conversations should not occur. But, when they do, it is a matter of 2nd use.
This may be my problem alone, but I really don't understand any of this; and that's probably because it seems to me that we Lutherans aren't consistent in the way we treat "Law." Just look at the so-called three "uses" of the Law -- they don't each refer to the same "Law," do they? It seems obvious to me that the second "use" of the Law refers to the whole of God's Law, since it is the attempt to live up to God's whole Law that so emphatically fails to justify us before God. If God's Law (in the second "use") serves as a mirror to show us our sin and to drive us to Christ, it is the very integrity of God's singular Law that "mirrors" the lack of integrity in our broken attempts to fulfill it.
But the first "use" of the Law cannot refer to God's Law as the second "use" does, can it? The first "use" is for curbing lawlessness in the civil realm, to constrain those who would do evil to harm the neighbor. But we use a vast ensemble of common law and statute law to maintain civil order, and not much of it resembles God's Law as portrayed in the Scriptures. We don't think that it is an appropriate "use" of God's Law to punish those in civil life who covet, or who neglect to remember the Sabbath and keep it holy (at least, not lately; and not in Texas). So the first "use" of Law must be indicating a different type of Law than the second "use" indicates. Right?
And the third "use" has got to be something else entirely, doesn't it? The third "use" of the Law is allegedly to guide sanctified believers into God-pleasing behaviors. But these sanctified believers are also sinners, right (simul iustus et peccator)? How do we know they are sinners? The second "use" tells us so. Therefore, the second "use" tells us we cannot live up to the standards of God's Law, while the third "use" tells us we should guided by God's Law in how we live. How can the same Law -- God's Law -- tell us two such contrary things? It looks like the second and third "uses" cannot be referring to the same Law, when one "use" says "you'll never succeed in doing it," and the other says, "do it, anyway."
I've always been baffled how anyone can see these as three "uses" of the same Law, when it seems that we are speaking of three different types of Law here. And so I think Lutherans would do well to reflect more seriously on just what we mean when we talk about "Law."
Yes, yes, I know: these are the sorts of misguided questions that could only be raised by someone who is addicted to relying on reason and logic to figure things out, instead of just falling back on faith to illumine the paradoxes. But I gotta tell ya, doing the latter sure makes theology and "getting a handle on this third use thing" a lot more difficult.
Tom Pearson