“It has become a deplorable custom that the Gospels and the Epistles are treated like law books, in which one is to learn what we are to do, and in which the works of Christ are presented as nothing but an example held before one’s eyes. Wherever this errant opinion remains within the heart, there neither gospel nor epistle can be read usefully and in a Christian way; such readers remain nothing but heathen, as before.”
Luther rightly sees that all of the imperatives (do this!) are grounded in the indicatives (Christ did this). Reading the New Testament any other way is to read it sub-Christianly.
On a lighter note, if you are looking for a great way to insult friends consider the Luther Insult Generator.