From Dr. Martin Luther's Lectures on Galatians (1535), commenting on chapter 4, verse 9:
"St. Paul is deeply amazed that those who already know God through the Gospel have been seduced by the false apostles and turn back again so quickly to the weak and beggarly elements. In the same way I would regard it as surprising if our church—which has, by the grace of God, been beautifully established in pure doctrine and sound faith—were to be subverted by some sermon or other from a fanatic and thus were to refuse to acknowledge me as its teacher any longer.
"And this is what will happen someday—if not during our lifetime, then after we have died. Then many who want to be masters will arise; under the pretext of piety they will teach perverse doctrine, and in a short while they will subvert everything that we have built up over a long period of time and with great effort.
"We are no better than the Apostles, who during their lifetimes witnessed the doleful sight of the overthrow of the churches that they had planted by their ministry. Therefore it is not surprising if we are forced to witness the same evil today in the churches where the sectarians are in control; and after we are dead, they will take over other churches as well and will infect and overthrow them with their poison. Nevertheless, Christ will continue to reign to the end of the world, but in a wondrous way, as He did under the papacy" (Luther's Works, Vol. 26, CPH 1963).