Antinomianism
The claim that because Christians are saved by grace, the Law has no further business with them. Luther fought this in the 1530s against Johann Agricola, who had been his own student. The Lutheran answer is that the Law still accuses, still restrains, and still instructs. That is what the Third Use of the Law is arguing about.
In Doctrine — What Lutherans teach, and where it differs from neighbouring traditions.