Satan has chosen a most certain, fascinating delusion, one that is calculated to take hold of the sympathies of those who have laid their loved ones in the grave. Evil angels assume the form of these loved ones and relate incidents connected with their lives and perform acts which their friends performed while living. In this way they deceive and lead the relatives of the dead to believe that their deceased friends are angels hovering about them and communing with them. These they regard with a certain idolatry, and what they may say has greater influence over them than the word of God. These evil angels, who assume to be dead friends, will either utterly reject God's word as idle tales, or, if it suit their purpose best, will select the vital portions which testify of Christ and point out the way to heaven, and change the plain statements of the word of God to suit their own corrupt nature and ruin souls. With due attention to the word of God, all may be convinced if they will of this…
"For there shall arise false Christs, and false prophets, and shall shew great signs and wonders; insomuch that, if it were possible, they shall deceive the very elect."
Both passages warn about deception through signs and wonders. Matthew 24:24 speaks of false Christs and prophets deceiving even the elect, while EGW describes evil angels impersonating loved ones to deceive. The common theme is deception through supernatural means.
"Even him, whose coming is after the working of Satan with all power and signs and lying wonders, And with all deceivableness of unrighteousness in them that perish; because they received not the love of the truth, that they might be saved."
Both passages discuss Satan's deceptive power and the use of 'lying wonders' to deceive those who reject the truth. EGW's passage elaborates on a specific form of this deception (impersonating the dead), while 2 Thessalonians provides a broader description of Satan's methods.
"Deceived mortals are worshiping evil angels, believing them to be the spirits of their dead friends. The word of God expressly declares that the dead have no more a portion in anything done under the sun. Spiritualists say that the dead know everything that is done under the sun, that they communicate to their friends on earth, give valuable information, and perform wonders. Psalm 115:17 : “The dead praise not the Lord, neither any that go down into silence.” Satan, transformed into an angel of light, works with all deceivableness of unrighteousness. He who could take up the Son of God, who was made a little lower than the angels, and place Him upon a pinnacle of the temple, and take Him up into an exceeding high mountain to present before Him the kingdoms of the world, can exercise his power upon the human family, who are far inferior in strength and wisdom to the Son of God, even after He had taken upon Himself man's nature. 1T 298.2"
"The dead praise not the Lord, neither any that go down into silence."
Ellen White directly references Psalms 115:17 in this passage.