[Trampled by Lambs]

Yeah, the song is a little sappy but I like it. He's asking you to imagine these things not necessarily live them. Utopian, yes but a world "living life in peace" is not such a bad thing to imagine, realistic or no. Thats what imagining is all about, eh?

[Hillary's Folly]

He's asking you to imagine these things not necessarily live them.

True, I don't think anyone denies that, but all the author is doing is asking people (particularly those people who believe in a one world utopia) to imagine the consequences of such a world. Nothing wrong in that, eh?

[August West]

Actually, he is asking the listener to consider that an alternate reality does, in fact, exist; that's why it's "Imagine there is no heaven...", not "Imagine there were no heaven.." Although extremely subtle, the use of the verb "imagine" followed by the indicative mood (rather than the subjunctive mood) is pure genius - not that I agree with the premise of the song, but it is pure genius.