It is God’s will and command that in His Church His Word be preached and believed in purity and truth, without adulteration. In God’s Church nobody should utter his own, but only God’s Word (1 Pet. 4:11). Chaff and wheat do not belong together. All “teaching otherwise,” ετεροδιδασχαλειν, is strictly forbidden. 1 Tim. 1:3: “As I besought thee to abide still at Ephesus when I went into Macedonia, that thou mightest charge some that they teach no other doctrine.” It is important to point out again and again that in all Scripture there is not a single text permitting a teacher to deviate from the Word of God or granting a child of God license to fraternize with a teacher who deviates from the Word of God. God is against the prophets who proclaim their own dreams (Jer. 23:31 f.). And all Christians without exception are commanded to avoid such (Rom. 16:17; 1 Tim. 6:3ff.).
from Francis Pieper’s “Christian Dogmatics”
Thanks to Jim Pierce.