Lets accept that you are in the spiritual world and God speaks to you,
"You are in my spiritual world and you can hear me speak to you. How would you like to leave this place where you can see and hear me and go to a place where you can't see or hear me and learn how to please me."
"Oh, and I would like you play the role of a demon, because even though I made this planet the way I want it to be, now I think the planet needs a demon."
So Darrell, I just need to know a few more things before I can answer this question.
Why didn't you ask him why you couldn't learn how to please him in the spirit world?
How were you going to know if you were doing it right on the planet here if you couldn't see or hear him anymore?
If he made the planet the way he liked it, why does he want some demon to change it?
If now he wants the planet changed, then I really wish you had asked him why he just didn't make it the way that he liked to start with? ( He is god afterall.)
And you really should have asked him what sort of demon? Water demon, fire demon, earth demon, air demon, slug demon, crumbs the pidgeons are about to pick up demon, making cars run out of petrol on the freeway demon, making icecreams fall off cones on a summers day demon or asking questions on hubpages demon?
Lastly Darrell, do you really think that your god wants you to be a demon on the planet. Isn't it possible that it is the great liar pretending to be god and not god at all. If somehow you managed to get sent to the planet by the bad guy trying to trick you, turn the tables on him. Instead of playing demon for this liar, do something positive for god and and be an angel on the planet, maybe you will find a reward other than returning to the pits of hell when you are finished with .
(a few suggestions for angels are - angel of giving directions, angel of wishing a nice day and be an angel and make us a coffee.)