I've been pondering this statement daily since.
If we go back to the Garden of Eden, we see that God cursed the soil (work), and He cursed childbirth (children). As I've previously written, God did this because: a)men will put their work before God and family; and b)women will put their children before God and family. So, the curses are designed to keep us putting God first, but they are still curses.
This means that life on earth is cursed. It may have been gracious for God to curse life on earth, given our idolatrous hearts, but it's still cursed. Life, in other words, is not the best.
The fact that life ends in death confirms this. If there is a God who cares about us, He wouldn't leave us in a perpetually cursed world. In fact, the flaming swords at the Garden of Eden were put there so that man couldn't sneak back in, eat of the Tree of Life, and live forever in this cursed world.
So, I think the fact that life ends in death confirms that there is an afterlife--at least if God is merciful. In PZ's latest book, he describes the one word that a "floater" (someone hovering on the ceiling of his hospital room over his dying body) needs to believe about God--mercy.
If God is merciful, then we can expect that He has prepared something better for us. Indeed, Jesus confirmed this. "In my father's house, there are many rooms. I go there to prepare a place for you."
So, why life? Perhaps it is because we can't understand mercy without having experienced non-mercy. This morning, Tullian wrote that: "at age 25, I thought that I could change the world. At age 42, I know that I can't change my wife, my kids, my church, and certainly not the world." This turned Tullian more and more to God's grace. This turns me more and more to God's grace.
The afterlife is going to be that much greater, because we have lived in this world. Yet, we are not to reject this world. If Jesus came into this world, and lived amongst us (exhibiting love to all), who are we to think that we shouldn't embrace this world and live out lives of love towards our fellow man?
The Kingdom, which Jesus discussed over and over, is already, but not yet. It has broken through into this world, but not fully. The best is yet to come.