This is roughly a bad paraphrase of something interesting that was said at church last night...
Many atheists / agnostics / philosophical materialists (people who say that matter is all there is) / etc say that believing in God is stupid.
But if you say that matter is all there is, then before too long (on the time scale of the universe), humanity will be extinguished, either by our own actions or by the slow death of the Sun. And everything that everyone has ever accomplished will be worth precisely nothing. There will be no memory of anyone; there will be no consciousness to observe our remains - nothing and the universe will carry on as if we had never existed.
In the light of that, it seems at least as crazy for an atheist to attach meaning or significance to anything ever done by anyone as it does to say there's a God who transcends it and who can provide meaning.