God can be proved imaginary by saying "Get Real" to a believer?
That illustrates nothing more than a blind spot in one's reasoning. Would you believe someone if he told you that God was real and that you should get real for not believing in him? I highly doubt it; so why would you expect them to believe you for telling them to get real for believing in him?
Furthermore, the whole issue of proving whether God is real or imaginary is, for all practical purposes, immaterial. I can point to something wholly fictional, that everyone knows is wholly fictional, and yet demonstrate that it exists even though it is not real, has no substance, cannot exert any influence on us, and cannot be objectively observed in any way. For example, Tolkien's Middle-Earth. I can safely say that this is almost certainly fictional and has never been observed objectively, etc.
Yet it exists. Everyone who has read Tolkien's books about it, or seen the movies, or whatever else you want to pick, gives it that existence. It may be imaginary, subjective existence, but it is still existence. The only way for it to stop existing would be for it to vanish out of the minds of everyone who has ever heard of it, and for all of the media which contains information on it to also vanish or be destroyed.
And that's the point about trying to prove that God is imaginary. I don't doubt that you guys can prove beyond a reasonable doubt that the Christian God doesn't exist as described by the Bible. I also don't doubt that you can pick apart a person's belief in God to the point where they have nothing left they can use as objective proof. But how can you get at a person's subjective belief against their will (without being able to coerce them)? Unless they're willing to listen, unless they're willing to buy into your reasoning, you can spend days, months, years talking about it and not get anywhere. And if they're hard-headed enough, they might even be able to reinforce their belief from the argument.