Craig’s example of the stranded astronaut . . . admits of a similar reply. Contemplating the predicament of a man who has nothing but a rock to sit on and must endure his solitude for all eternity does indeed come close to contemplating something meaningless. But this is simply the result of the fact that, by completely isolating the man, the example surreptitiously removes the vast majority of human goods from his life. Let the man be on the Earth, not on an asteroid lost in space. Instead of being alone, let him be surrounded by family, friends, and opportunities for growth and understanding. Let him live a human life with access to the full range of human goods. Suddenly, it is no longer obvious that his life would be meaningless. If it were a finite life, it would still contain many important goods capable of carving a niche for meaningfulness in the face of any suffering the man may endure along the way. And if he inadvertently drank the potion for immortality, as in the example Craig cites, the man would not sink into despair as long as, for example, the people who are important to him drank the potion too, and they could all reasonably expect to continue to enjoy the moral and intellectual goods that are available to them now. An infinitely extended human life endowed with goods of the moral sort is in fact the model for theistic conceptions of the afterlife. So, with the appropriate modifications, the example of the man inadvertently drinking the potion for immortality does not lead to the conclusion that life, even if infinite, is meaningless without God. Rather, the modified example reveals that worthwhile relationships, understanding, and love are the ultimate sources of meaning for a human life. By themselves, without any need for a God to exist, they give our lives their significance and value, so much so that even theists craft their idea of eternal beatitude from the idea of a life where the supply of these goods never ends.
-Di Muzio, Gianluca. "Theism and the Meaning of Life", Ars Disputandi 6:1 (2006), pp. 138-139.