well I for one don't think America is going to end any time soon.

And that's what the song is saying, surely mary - it's a strike against the things that are threatening to destroy what America is supposed to be about. When you get down to it, they are the same things that have always been trying to pull you down and twist you into something that, instead of being the hope of the world are a cancer on the world. They've never succeeded so far.