...all the wretchedness and misery rampant in the world is the work of the devil, who delights in bringing ruin and death on man; for it was he who plunged all human nature into sin and death. But, as we learn from 1 John 3:8, “the reason the Son of God appeared was to destroy the works of the devil” and to re-establish the divine works of life. This He proved so forcefully that even the Jews had to admit grudgingly that no man could perform such works. And even though they declared that no one but God could forgive sin, still His works stood before their eyes in testimony that He had this divine power and that He was the Man who could help man from death to life, against sin to righteousness, from strife to peace and every good. Thus we become assured not only of the doctrine that Christ is true God with the Father, but also that He is a merciful God and Savior; and we can recognize and apprehend the Father’s heart and will in all the works of the Lord Christ, for the true and blessed consolation of all wretched and aggrieved hearts and consciences. “Thus,” says Christ, “My works will aptly demonstrate to you that the Father is in Me and wants to be known through Me.”
But you say: “After all, the devil can work miracles and signs like Christ’s. How, then, can we found our belief on the miracles of Christ?” It is true that the devil can torment people and lay them low; or he can blind them temporarily or lame a member, as he often did through his witches and devilish whores, and then heal them again. Not that these people were really blind or lame, for to such he could not restore sight or a member; but he bewitches the people and dupes their five senses, so that they do not know better and are willing to swear an oath that it is real.
At times the devil also takes possession of a person and then lets himself be cast out by adjuration, blessing, etc. All this he does for the purpose of confirming his lies and deceptions and of impressing the people, so that because of these apparently great miracles they are seduced into idolatry. This he has accomplished to date with pilgrimages and the idolatrous adoration of saints, at one place with the Sacred Blood, at another with this or that Mary. He has filled the entire country with shameful delusions and has prompted people to throng to such places and everybody to make vows there and transfer their trust from God to his lies. For in the end it was nothing but devilish deception with which he made fools of the people and persuaded them to believe that they had really been helped.
Yes, the devil can contrive to make a person who has been wounded, shot, or injured in some other way appear to be dead; he can render a person insensate for a while, with the result that everybody believes that he is really dead. Later on, however, this person regains consciousness, and then people say that he has been brought back to life through the power of this or that saint. Thus I have heard of a lad who had been lying submerged in water for two days; but when his parents took him and pledged him to St. Anne, he was restored to life. Are these not also miracles and signs? No, for surely these people were not actually dead. The devil so befuddled people’s senses that they thought them dead until he let them regain consciousness.
Thus we read in the lives of the old fathers about St. Macarius. He was approached by a married couple with a beautiful daughter whom the devil had bewitched so that her parents and everybody else took her for a cow. They brought her to Macarius in the wilderness and lamented that their virgin daughter had been changed into a cow by witchcraft. They implored him to ask God to restore her to her original form. But he said: “What has happened to you? I see nothing but a beautiful, healthy virgin. Therefore this must be nothing but deception with which the devil is duping you and deluding your five senses.” Finally he prayed over her and also bade the parents pray. This was the end of the deception, and the parents and others again saw their daughter as before.
I am saying this to keep you from believing in all sorts of miracles and signs. For in Deut. 13:1 ff. Moses predicted that false prophets would also perform these. And in 2 Thess. 2:9 St. Paul clearly foretold that Antichrist’s reign would include all kinds of miracles and signs wrought by the devil. Therefore we must judge and consider all wonders and miracles in the light of God’s Word, to ascertain whether they are in accordance and agreement with it. If anyone directs you to any help other than the doctrine and the works of the Lord Christ, you can conclude freely that this is the devil’s work and his false miracles, by means of which he deceives and misguides you, just as he has done so far under the name of Mary and the saints where Christ was never known or taught aright. As St. Paul declares (2 Thess. 2:11), God permits the false Christians to be tempted in this way; they have to believe lies because they refused to believe the truth.
And since God forewarned us regarding such signs, we should be circumspect, and we should look into and judge these signs. We shall see that they happen outside and without Christ, yes, contrary to His Word and the faith, which proves that they are nothing but false signs of the devil. For the devil cannot perform genuine miracles and wonders; but, just as he is a murderer and liar from the beginning, so his works do nothing but misguide and harm man. He poisons the air and kills people through pestilence and other plagues. When he afflicts man with an illusory evil or conjures up a specter before one’s eyes, he can stop later on. But when a man is actually dead, he is impotent; and even if he were able to lend a helping hand in such an instance, he is so wicked that he would not do it. Christ alone performs true, divine signs and wonders. Take, for instance, the time when He raised Lazarus, who had lain in the grave for four days, or when He brings back to life and health those who have been killed, destroyed, or injured by the devil. Furthermore, He exposes the devil’s fraud, lies, and deception, with the result that the devil is recognized and must stop. The devil does not pursue the Christians long with his hocus-pocus. For he is an arrogant spirit who wants to possess hearts and consciences only to induce people to believe his lies and worship him as God. Where he fails in this, he does not stay long. In times past there were many poltergeists and hobgoblins everywhere; they frightened the people into doing whatever they demanded of them. This was because the devil was not recognized and these hobgoblins were considered poor souls. But now that he is known, he desists from this game. Today he seeks different ways of casting a spell on the people and deluding them; this he does through his corporeal poltergeists and factions.

(“Sermons on the Gospel of St. John,” Luther’s Works, Vol. 24 [Saint Louis: Concordia Publishing House, 1961), pp. 73-76)