What about faith healers and exorcists?
For one thing, no faith healer, so called, is casting out devils. Satan cant’ cast Satan out. So Oral Roberts and nobody else is casting out devils. The devil isn’t casting the devil out. Now some of these faith healing things that they pretend to do I think [are] frauds but some of them may have some validity, I don’t know. The power of the devil may work miracles. Apparently the devil can work almost any miracle, but one miracle he doesn’t work is to cast himself out because of this great compelling desire to have a body.
One of the apostles about four or five months ago, had the Stake President say to him, “I have got a woman here in the Stake who is possessed with the devil and we want you to cast him out.” And then the next thing the Stake President said was, “The bishop tried and he failed.” And he said, “I tried and I failed.” So we thought better have this woman brought to you, and let you do it. They brought her and this member of the General Authorities was on the spot, and he tried and he failed. This woman was like this man at the tomb. The devil was speaking by her mouth so that it was the voice of the devil coming out—it wasn’t hers. They brought her into the room and she went off into a tirade of railing, bitter invective cursing of the Lord and the brethren that were there and everything else. And so they administered to her and they tried to cast the devil out and the devil didn’t leave. And then they got through the voice of this woman went off into terrible hysterical laughing, totally beyond what normal individuals would do; the devil laughing through her. And the phrase that the devil was saying was, “You thought you could cast me out, didn’t you, and you can’t.” And then he would laugh and deride them, mocking them for not being able to cast him out. I don’t know everything that happened, but by that night the devil was gone. They brought the woman back and she was perfectly normal and all right. She knew the instant the devil left and was aware of the fact that it left. So it was just a delayed reaction and it did work, but it didn’t work immediately.
In the episode of the swine it didn’t work immediately with Christ. He said, “Depart,” and the devil stayed there long enough at least to argue with him and say, “Don’t cast us into the deep before our time,” and he agreed, and they said, “Let us go into the swine,” and he agreed. So there was a little interval, a moment or two there, where the devils resisted and then they left. (Bruce R. McConkie as cited by Dennis Horne, Faith to Heal and to be Healed [Springville, Utah: Cedar Fort, 2009], 190-91)