Over against the factious spirits and false preachers, this fact stands sure: When the Holy Spirit comforts, he does so in no other way than to witness of Jesus and picture him in the human heart. In contrast, the evil spirit, by emphasizing sin and death, frightens the conscience. This the Holy Spirit must combat through his witness as he speaks through the Word to our hearts: Hold on, man, what are you up to anyway? Can’t you think of anything but sin, death, and damnation? Take your eyes off this gruesome, frightening sight and look here; don’t you know the man named Jesus Christ, of whom it is written: conceived by the Holy Spirit, born of the Virgin Mary, suffered under Pontius Pilate, was crucified, died, and was buried, descended into hell, and on the third day rose again, and ascended into heaven? Who do you think this happened? Was it not that you might have consolation against death and sin? then stop being frightened and so despondent; you have no reason! If Christ were not with you and upholding you, and had not done these things for you, then you would have reason enough to be frightened. But he is with you, around you, and he says, “Lo, I am with you alway, even unto the end of the world.” For that reason he suffered death for you, and for your consolation and safeguarding he is seated now at the right hand of his heavenly Father.
Martin Luther, House Postil for the Seventh Sunday of Easter (John 15:26-16:4)