“It is true, I have, by and large, sharply inveighed against ungodly doctrines and have not been slow to bite my adversaries, not because of their bad morals but because of their ungodliness. Of this I am so unrepentant that I have resolved to continue in this burning zeal and to despise the judgment of men, after the example of Christ, who in His zeal called His adversaries a generation of vipers, blind, hypocrites, children of the devil (Matt. 23:13; 17:33; John 8:44).
And Paul calls the sorcerer a child of the devil full of all subtlety and all mischief (Acts 13:10); and some false apostles he calls dogs, deceivers, and adulterers of the Word (Phil. 3:2; 2 Cor. 11:13). If these sensitive ears had heard this, they would probably say that no one could be more biting and immoderate than Paul. Who is more biting than the prophets?
But nowadays, of course, our ears are made so sensitive by the mad multitude of flatterers that as soon as we find that we are not praised in all things, we cry out that people are vicious; and when we cannot ward off the truth under any other guise, we escape from it under the pretext of the snappishness, impatience, and immoderateness of its defenders.
What good does salt do if it does not bite? What good does the edge of the sword do if it does not cut? Cursed be the man who does the work of the Lord deceitfully!”
–Martin Luther, What Luther Says: An Anthology, Vol. 1, comp. Ewald M. Plass (St. Louis: Concordia Publishing House, 1959), entry no. 3363, 1057.