|Luther said this specifically about Baptists,|
but Missouri and WELS run to the Baptists to learn how to "do church."
For every sect has always had one or more particular hobbies and articles which are manifestly wrong and can easily be discerned to be of the devil, who publicly teach, urge and defend them as right, certain and necessary to believe or to keep. For the spirit of lies cannot so conceal himself, but that he must at last put forth his claws, by which you can discern and observe the ravenous wolf. Of this you have an example and testimony in all the well known fanatics and false spirits; as in our time the Anabaptists, of whom it is manifest that they are wrong in their teaching concerning Christ, faith and the sacraments. They regard baptism as a common, naked, empty sign, despise the external spoken and written Word and Scripture, pretend to have special revelations independent of the witness of God’s Word.
Luther's Third Sermon on Matthew 7:15ff. Baker Book series.