That's hilarious. I think the best part is where it points out that since particles have positive and negative charges and 1 + -1 = 0, then the universe must have been made "from nothing". Astounding.
Well, if the theoretical demons were to come out of the hole, they'd either have to be in-part non-corporeal or they'd have to be skinny demons (look how narrow the hole is). Or maybe they were demon mice, able to squeeze through narrow gaps in the earth. Then again, if they were non-corporeal, I don't think they'd need a hole to come through, unless they were demon gas.
It's not. At least i don't think it is. It's part of some old spam that used to go around the Internet and I know at least a few folks take it seriously; you know, that same folks who are still pushing geocentrism.
http://www.orthodoxengland.org.uk/demonsscr.htm