“There are two parts to this text. Christ says clearly: ‘The Holy Spirit, whom the Father will send in My name’ and ‘He will teach you all things and bring to your remembrance all that I have said to you.’ The most important words are ‘in My name’ and ‘all that I have said to you.’ These words they dismiss from their mind and overlook, as though they were nothing or were spoken by a fool. But my dear devil, it will never do to dismember and mutilate a text! Put your spectacles on your nose, and either look at the text in its entirety or keep your hands off it altogether. Christ says that it is to be the Holy Spirit’s office to teach Christendom the Word of the Lord Christ and to bring it to mind. And later (15:24) He says: ‘He will bear witness to Me,’ and ‘He will glorify Me’ (16:14). He does not say: ‘He will confer on the church the power to resolve and order what it pleases about God’s Word. It is not the Holy Spirit’s office to alter Baptism, the Gospel, and the Sacrament, or to institute new laws and ordinances. No, it is His office to deal solely with My Word, ordinances, and commandments, to implant these in you and to teach you what I have said.’
With this support it is an easy matter to reply to the devil: ‘I do indeed hear your awesome words ‘Christian Church’ and ‘Holy Spirit,’ before which everyone is to bow without a word of contradiction. But I also insist on hearing what and who the Christian Church is and what is called the Christian Church. Let us agree on the definition, that we may understand the language’” (Luther’s Works, v. 24, p. 173).