Talking about the alleged absurdity of life if there is no God confuses the true issue. The existence or non-existence of God is not the real point here, since I'm sure that the author would readily agree that his life would still be meaningless even were God to exist, but if at the same time his soul were nonetheless to simply "revert to nothingness" after he dies.
Some may feel that that is a subtle distinction, but I think that it's important to distinguish between the supposed "absurdity" of life per se given the non-existence of God and the "absurdity" of life in spite of the existence of God, but if Man possesses no immortal soul.
Does anyone follow me here, and could they imagine their lives nevertheless having meaning, even if of limited duration? (After all, most sincere believers will readily confess that they can't know that they'll be "saved.")
You're acting as if the latter is an option. It's not. God has been kind enough to spell out the alternatives and that's not one of them. Since I'm not aware of any religion that doesn't have some sort of eternal reward belief system, there are one of two options: either God doesn't exist and we turn into dust or God exists and there is some sort of eternal reward for our beliefs and/or just life.
(After all, most sincere believers will readily confess that they can't know that they'll be "saved.")
I don't believe this to be true. A true believer knows that he will be saved. That's why he is a believer. I think the closest that you get is what CS Lewis describes as moments of doubt brought on by changing moods. But these changing moods, in most cases, do not shake our faith, because if they did, we would not be believers. The core of our faith is that we believe that Christ saved us and we will have eternal life in Heaven.
Another way to think about it, Alexander, is rock climbing. Let's say I'm rock climbing, and I have a safety harness that is attached to a rope that is tied off so that I cannot fall. At times, I may be unsure of my footing and I have a momentary fear that I will fall, and I have this fear despite knowing perfectly well that I am safe and secure by virtue of the rope and safety harness. As long as our foundation is built on the rock of Christ, our foundation is firm and we are safe and secure. That doesn't mean that we don't doubt our footing from time to time, but we know our foundation.
I DO see your point, and I think Craig saw it too. Eternity is an essential element of the Christian tradition, and Craig very much makes it part of his argument.
Some things would have force even if we ceased to exist but there was a Creator God. Moral laws, for example, which have no force if we merely evolved, and have no more value than worms - but DO have value given the Imago Dei - would still hold power.