There have been exchanges between P.Z. Myers and Jerry Coyne on the question of what evidence, if any, would persuade them of the existence of God. It came to me recently that an excellent bit of evidence on the side of theism would be if Tolkien’s Elves were real: a race of beings very like humans, but not subject to death from old age.
I have never lost my deep affection for The Lord of the Rings, which I have read countless times since early adolescence. The mythology concerning mortality, whereby endless life was the gift of the creator god to the Elves, while death was, in intention, the corresponding gift to humans (a gift that we failed to appreciate, causing much woe) made a big impression on me.