Satan is a defeated foe; therefore his power is limited, but he still has the ability to “deceive the whole world” (Rev.12:9). Jesus said, “The devil . . . does not stand in the truth, because there is no truth in him. Whenever he speaks a lie, he speaks from his own nature; for he is a liar, and the father of lies” (John 8:44). Satan has no authority or power over you except what you yield to him when you are deceived into believing his lies.
Niel T. Anderson, Victory over the Darkness