Referring again to the 1st, 2nd and 3rd uses of the law. Although I've seen 3rd use referred to as either exhortatory or didactic, I'm not sure what the difference is. To say that something teaches without exhorting is a false distinction.
Nevertheless, I've traditionally argued that the 3rd use IS the 1st use. The civil use teaches and exhorts all on its own, and the Christian, after hearing the gospel (3rd use is always the use for those who have already heard the gospel), is thrown immediately back into the world of vocation and life in the world. Therefore subject to the 1st use the same as everybody else.
The gospel, on the other hand, never exhorts. It is not didactic. Instead, it sets free. It says, "You are free indeed, for Christ's sake."