Spirits of devils impersonating relatives or friends will appeal to our tender sympathies and will work miracles. We must resist them with the Bible truth that the dead know nothing and that they who appear this way are the spirits of devils. LF 228.3
All whose faith is not established on the Word of God will be deceived and overcome. Satan works “with all unrighteous deception,” and his deceptions will increase. But those who are looking for a knowledge of the truth and who purify their lives through obedience will find a sure defense in the God of truth. The Savior would sooner send every angel out of heaven to protect His people than leave one person who trusts in Him to be overcome by Satan. Those who comfort themselves with the assurance that there is no punishment for the sinner, who reject the truths that Heaven has provided as a defense for the day of trouble, will accept the lies that Satan offers, the deceptive claims of spiritualism. LF 228.4
Scoffers ridicule what Scripture says about the plan of salvation and the punishment that will fall on those who reject truth. They pretend to have great pity for minds so narrow, weak, and superstitious as to obey the requirements of God's law. They have yielded themselves to the tempter so fully, united with him so closely, and drunk so deeply of his spirit that they have no desire to break away from his snare. LF 228.5
Satan laid the foundation of his work in the assurance he gave to Eve in Eden: “You will not surely die.... In the day you eat of it your eyes will be opened, and you will be like God, knowing good and evil” (Genesis 3:4, 5). He will reach his masterpiece of deception at the very end of time. Says the prophet: “I saw three unclean spirits like frogs.... For they are spirits of demons, performing signs, which go out to the kings of the earth and of the whole world, to gather them to the battle of that great day of God Almighty” (Revelation 16:13, 14). LF 228.6
Except for those whom God's power keeps through faith in His Word, the whole world will be swept into the ranks of this deception. The people are quickly being lulled into a fatal security, and only the outpouring of God's wrath will awaken them. LF 228.7