This has been an interesting thread. It seems that there are two views regarding the power of demons. One is that their power is based on deception, their basic strategy is to deceive. Another holds that they have power in more objective ways. Anecdotal evidence at times seems to support one view, at times seems to support the other. I thought the terminology of an "excluded middle" was very helpful, and applied to a lot of the Enlightenment thinking that seems to be popular even among Reformed Christians. But I wonder if characterizing those who hold to the first view, that all demonic power is based on deception as "excluding the middle" is altogether accurate. If all demonic activity is deceptive, it makes sense that one of the things the demons would deceive about is precisely the nature and scope of their abilities. I think you can illustrate it from temptation. A factor in some temptations to sin is that they seem to come with a feeling of inevitability: "you know you're going to give in eventually, why not now?" If you accept the premise, "you will inevitably give in to temptation" then you usually do; but when you see that this premise is a lie, the temptation loses a lot of its force. So if demons can convince me that they have some sinister powers and bring me into fear, have I not thereby given them a power over me that they would not otherwise have had because I believed their lie? It seems to me from Ephesians 6 that God has given us two weapons in spiritual warfare: the sword of the Spirit, which is the word of God, and prayer. And Martyn Lloyd-Jones, who did not exclude the middle, by any means, taught that in dealing with demonized people you had to explain Biblical doctrine, give them an overview of Scriptural teaching on the most prominent doctrines. So it is not by exorcistic rituals, but by meditation on and proclamation of God's word, accompanied with fervent pleas for understanding and faith that demons are vanquished. As we see the truth, their lies lose their force, and they lose their power.