In my last post I spoke of our life on earth and how its significance pales when compared with the life that is to come and, in a way it does, but it may also be that our brief time here might be the most important part. Just think, something about our experiences here are so significant and worthwhile that God was willing to risk our eternal soul in order for us to have these earthly experiences.
He could have (and did in the form of angels and other heavenly beings) simply made us purely spiritual beings, could have skipped earth and just had us in Heaven (that's not to say that we couldn't have still rebelled, obviously some of the angels did, but I think our rebellion would have been less likely and maybe the angels rebellion as well). But he created earth and, though he may not have originally created it with death, decay, and temporariness, he knew it would become such. He knew that our bodies would break down, knew they were fallible, and the world we live in breakable but he was willing to risk it, risk us because there is something here which we can gain.
I won't pretend to know what that gain is, but I will attempt to guess. First, maybe it was just so the God-head could enact the ultimate display of love through the life and death of the Son on earth. If the world had never been created, if the eternal Heaven was all there ever was, God could tell his creatures “this is how much I love you, I would become temporal, fallible, breakable, 'temptable.' I would be broken for you, allow you to tear my heart to pieces, and then offer to save you. I would be a sacrifice for your sake” and it would be no less true than it is now, but in acting that out on this little ole earth I think it changed something about reality, about how heavenly creatures view the God they worship and creates a relationship for us to God that otherwise would be impossible (and I'm not just talking about how that Gesture solved our fallenness).
A life here on earth also perhaps allows us to appreciate certain aspects of God which we would not find as awe-inspiring had we not experienced decay, fallenness, the breaking down of all around us, and pain. Perhaps through our seeing so much imperfection, we will better be able to see perfection.