The daily Luther
7th June
But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you.
John 14 (xxvi)
All these gangs lay claim to the Holy Spirit, so that people will believe them. But if we look at this saying and at others like it, then we are able to judge correctly and to reject anything that is contrary to it. For these people bring what they want to bring. Now, I truly know what my Lord Christ says and what I should believe. So if somebody comes along and tells me something that is supposed to have been taught and revealed by the Holy Spirit, then I shall stay with this Word and test his teaching against the true touchstone. If I see that it matches what Christ says, then I shall allow that it is right and good. If something is being changed, however, then I shall say: "You are not the Holy Spirit! You are the very Devil! The true Spirit comes in no other name than in the name of Christ and teaches nothing other than what Christ taught."
The complete Luther - "A Meditation for Each Day of the Year" is available as a biligual (English and German) BREVIARY published by Wartburg Verlag Weimar. It can be purchased in English, world-wide from most internet book shops.