ANSWER: Your difficulty arises from several erroneous conceptions: (1) That the moral government of God is an appropriate sphere for the exercise of physical omnipotence. Free agency excludes it, having no more relation to it than the eye has to a symphony and the ear has to a rainbow, and an earthquake has to the shaping of a geometrical demonstration. A free agent is the first cause of his own moral acts. God can prevent the evil choice of a free agent only by uncreating him. (2) The devil is one personality. The scriptures teach that there is a multitude of evil spirits. (3) That the evil one, or the combination of fallen spirits, is omnipotent is a great mistake. (4) That Satan is omnipresent, because temptation to sin is going on everywhere at the same moment. For aught that we know the tempters may outnumber the tempted, a legion (6,000) besieging one soul (Mark 5:1, 15), the name Satan or devil being conceptually applied to the whole number, because our minds in this way more easily and vividly wield the total of bad spirits. Davenport, the ablest theologian of all the New England Fathers, in his catechism thus answers the question, "What is the devil?"
The multitude of apostate angels which, by pride, and blasphemy against God, and malice against man, became liars and murderers, by tempting him to that sin.Eliminating from your mind these errors there is no more difficulty in believing that evil spirits exist in the spiritual realm than that they exist in the physical realm. It is true that a man may be drawn away by his own lust; but this does not explain the temptations of Christ. He talked with wicked spirits, not with something impersonal.
— Steele's Answers pp. 165, 166.