How Satan and His Agents Work
I am instructed to say that in the future great watchfulness will be needed. There is to be among God's people no spiritual stupidity. Evil spirits are actively engaged in seeking to control the minds of human beings. Men are binding up in bundles, ready to be consumed by the fires of the last days. Those who discard Christ and His righteousness will accept the sophistry that is flooding the world. Christians are to be sober and vigilant, steadfastly resisting their adversary the devil, who is going about as a roaring lion, seeking whom he may devour. Men under the influence of evil spirits will work miracles. They will make people sick by casting their spell upon them, and will then remove the spell, leading others to say that those who were sick have been miraculously healed. This Satan has done again and again.--Letter 259, 1903. {2SM 53.2}
We need not be deceived. Wonderful scenes, with which Satan will be closely connected, will soon take place. God's Word declares that Satan will work miracles. He will make people sick, and then will suddenly remove from them his satanic power. They will then be regarded as healed. These works of apparent healing will bring Seventh-day Adventists to the test. Many who have had great light will fail to walk in the light, because they have not become one with Christ.--Letter 57, 1904. {2SM 53.3}
Selected Mesages II, E. G. White, p.53.