Does your church have discernment? If I walked into a service with the intent of, say, faking a repentance at the altar, complete with "tongues", would your ushers swing me around and toss me out before I even had the chance? Or would they at least interrupt my fake tongues?
I've considered actually doing something like this. I'd announce here on AFF that I will show up at one of your churches with $100 in my pocket, which I would gladly hand over to the person who identified me as a fake, when I went to the altar and before I left it. You'd have to tap me on the shoulder and say "You are fake. Get out of this church and never come back." If and only if you said those words I would keep up the act as I walk out the building, with escort, and then and only then hand over the hundred bucks.
That would be easy for someone with discernment. If I could affort it, I'd make it even more interesting, with $1000 or more! But the real danger, of course, is that you falsely identify someone else as me. That poor guy would probably be devastated. Might even fall into despair. And that is why I will never pull this prank.
Other pranks, maybe. But not this one.
I'm discerning that you're possessed by a spirit named "stupid."
I didn't say it did. Do you think that discernment works only for discovering a devil in someone?
By the way, there is a passage that talks about determining whether a "spirit" is from God or not. I don't think it is referring literally and exclusively to devils that are, perhaps, occupying a person. 1 John 4 starts with that warning, then says the reason you should try spirits is that there are many false prophets. Not all false prophets are demon-possessed, are they?
Now, in the context of pranks, I seriously doubt that a prankster fake prophet would be struck dumb would be unable to pass the test given in 1 John 4. Ask him if he "confesseth that Jesus Christ is come in the flesh is of God". If he says "yes", do you have to accept him as a genuine prophet? I wouldn't, if I were you!
P.S. I am not saying that this passage refers to the gift of discerning of spirits. I'm just sayin'.
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Hebrews 13:23 Know ye that our brother Timothy is set at liberty