What's the deal with apples, anyway?

On Group 5's blog "Introduction to Authors", Sheryl wrote a post about how the end of Good Omens is essentially a direct connection to Adam and the Fall of Mankind by eating the apple in the Garden of Eden. In her post entitled "Apples....Again" she writes:

"There were numerous quotes from Good Omens that stick out in my mind, but one that is particularly humorous and thought-provoking to me comes right at the end of the novel. The quote goes, "And there was never an apple, in Adam's opinion, that wasn't worth the trouble you got into for eating it."

To me, this quote pretty much sums up the views of the Adams of both Good Omens as well as Paradise lost."

I, too, was really struck by this quote. But in addition to the humor which it provides, it struck me for another reason.
In class we've often talked about how John Milton's purpose in writing Paradise Lost was to explain the ways of God to man. As I was reading Good Omens, I kept trying to look for what Neil Gaiman and Terry Pratchett's purpose was, and whether it was similar or different to Milton's. As I stated in my previous post about choices, as I was approaching the end of the novel I came to the conclusion that choices were the central point of the novel; that our choices were what defined us, not who we were born to be. But I think, in the end, there's a little bit more to it than that.
After I got to the end of the book and I read the above quotation, I came to amend my theory on what Gaiman and Pratchett are trying to get across through Good Omens. I think what they're trying to say is that even when we might get in trouble for the choices we make, and even when those choices might directly contradict mandates from the powers which directly affect our lives, when push comes to shove the end of the world will probably take place when we least expect it, so we should make every choice according to what we believe to be right in our hearts because it could be the last decision we make on earth.