If you ask me, the best reason to think "life is meaningful" is because one's life seems meaningful. If you can't stop "acting as if my own life had meaning," it's probably because it does have meaning. Indeed, not being able to stop acting as if one's life is meaningful is probably what it means for life to be meaningful. But why think this has any logical or causal relationship to the scientific facts about our brains or lifespans? The truth of the proposition "life has meaning" is more evident and secure than any proposition about what must be true if life is to have meaning. Epistemic best practices recommend treating "life has meaning" as a more-or-less self-evident, non-conditional proposition. Once we've got that squared away, we can go ahead and take the facts about the world as they come. It turns out our lives are infinitesimally short on the scale of cosmic time. We know that to be true. Interesting! So now we know two things: that life has meaning and that our lives are just a blip in the history of the universe.This reminds me of sports. I watch a football game and it seems to have meaning. I find it very difficult to stop acting like it is hugely meaningful. But I know from logic it is not. Most things in the world will not change based on the outcome of this game. So what should I do? Should I follow my feelings or follow my logic? My feelings of course. Still I should temper that with the knowledge that they are not reflecting a deep truth. The deep truth is that it is only a game.
What Wilkinson seems to be suggesting is to hold two contradictory truths at the same time. People think that that is OK when it comes to religion when they would never do it in any other area of life. It isn't. If they are truly contradictory then one must be false. Which is more likely to be false? Science or your intuition? So you end up trying to avoid the conclusion that life is meaningless. Trying to avoid thinking deeply. That is a sad way to live.
But are these things really in conflict? Can our lives be infinitesimally short and meaningful? Well, yes. If that is not the whole story. Wilkinson is right not to look for meaning in life from science. He should not just look to his intuition either. At least he should not stop with his intuition. The only way such a small reality as a human life can be meaningful in such a large context as the universe is if it is connected with something much larger.
So when you are evaluating the truth claims of Christianity does it not make sense to note that it resolves this problem? People assert that atheism does not imply nihilism. Christianity would never assert something so irrational. It just wishful thinking. All the talk of "epistemic best practices" is just nonsense. Either there is a deeper truth about mankind and the world than science tells us or there is not. If there is not then life has no meaning. It becomes a tale told by an idiot full of sound and fury signifying nothing.
In the end atheism does exactly what they accuse religious people of doing. That is believing something irrational to avoid facing the meaninglessness of life. Christians at least accept that since our life has meaning beyond the physical world that has huge implications for how we should live. Believing there is meaning and denying the existence of the larger reality that could give it meaning leaves you in an odd spot. How can I make choices that are driven by the truth about what life really means? If it is just an irrational assertion not connected to anything then what do I do with it?