Assurance of Pure Doctrine Essential

 "In the first place, therefore, it is necessary that both preachers and hearers take heed to doctrine and have clear, unmistakable evidence that what they embrace is really the true Word of God revealed from heaven; the doctrine given to the holy and primitive fathers, prophets, and apostles; the doctrine Christ himself confirmed and commanded to be taught. We are not permitted to employ the teaching dictated by any man's pleasure or fancy. We may not adapt the Word to mere human knowledge and reason. We are not to trifle with the Scriptures, to juggle with the Word of God, as if it would admit of being explained to suit the people; of being twisted, distended and patched to effect peace and agreement among men. Otherwise, there would be no sure, permanent foundation whereon the conscience might rely." Martin Luther, Sermons, Baker, Vol III p. 325.