Moses strikes at and anticipates that hidden perverseness of heart by which many, when they hear the threats and curses of God, console themselves inwardly and say: “It won’t be so bad!” And so they continue smugly in their godlessness. Especially the work-righteous and the idolatrous people do this; for they are deceived by the beautiful appearance of godliness and do not think that the threats of the Law apply to them, as is seen in all the prophets. Just as true godliness naturally brings with it fear of God, so godlessness and hypocrisy produce smugness. Against this smugness of the wicked, therefore, Moses inveighs most bitterly down to the end of the chapter, just as all the prophets do; and he foretells that curses and devastations threaten these people especially, so that they, overturned like Sodom and Gomorrah, will be talked about and hissed by the whole world.
Luther’s works, vol. 9: Lectures on Deuteronomy 1525