Trick or treat? How does the devil trick us? He comes disguised as an angel of light (2 Cor 11:14). Below Luther tells of how Christ appeared to him and he dismissed the vision as an illusion of the devil:
“Christ once appeared visible here on earth . . . and according to the divine purpose of God finished the work of redemption. . . . I do not desire that he should come again in the same manner, nor that he would send an angel to me. No, even if an angel would appear before my eyes, it would not add to my belief; for I have my Savior, bond and seal; I have his Word, Spirit, and sacrament; on these I depend, and desire no new revelations. And the more steadfastly to confirm me in this resolution to hold solely by God’s Word and not to give credit to any visions or revelations, I tell you what happened to me: On Good Friday last, I was in my room in fervent prayer when suddenly appeared upon the wall a bright vision of our Savior Christ, with the five wounds, steadfastly looking upon me, as if it had been Christ himself corporally. At first sight, I thought it was some celestial revelation, but I reflected that it must be an illusion and juggling of the devil, for Christ appeared to us in his Word, and in a meaner more humble form; therefore I spoke to the vision: Away with you, confounded devil: I know no other Christ than he who was crucified, and who in his Word is pictured and presented to me. Whereupon the image vanished, clearly showing of whom it came.”
From Luther’s Table Talk (WATR I:287, 8-27)