“Therefore let us look at this text aright, keep it pure, and hold it properly before our noses. Christ says: ‘The Comforter, whom the Father will send in My name, will teach you all things.’ These words they ignore; they pervert them by saying: ‘The Holy Spirit comes in our name; whatever popes, cardinals, and bishops decide is done by the Holy Spirit.’ But ‘in Christ’s name’ means: wherever Christ is understood, known, and believed; wherever His Baptism and the office of the ministry are administered.
Furthermore, Christ says: ‘He will teach you and bring to your remembrance all that I have said to you; that is, He will teach you that it is My Word and doctrine. He will apply Himself to this and recall it to your mind, that you may understand and judge that it is My Word, the very words which I spoke to you. He will emphasize it and make it clearer from day to day, so that you will know Me ever better and see how through Me you are delivered from sin and death.’
That is my answer to our papists, who come strutting along with this verse. They praise the glorious name of the Christian Church. They say that the church is taught by the Holy Spirit and that for this reason its dictates must be obeyed. That is true and correct. But it is important to discern who is and who is not the church. Christ says: ‘You can observe and judge this by the presence or the absence of My Word. The Holy Spirit shall come in My name and teach what I have said. But if its teachings are different from, and not in harmony with, My Word, then it is not the Christian Church. For how could the church alter or pervert the Word of its Lord?’” (Luther’s Works, v. 24, p. 175-176).