I've read some of CS Lewis' writings on religion. I'm an atheist married to a person of faith, so I'm interested in what the people I love find so compelling about their faith.
He's a very charismatic writer, but sneaky in his arguments. For example, my rebuttal to the above would be: "Humans are evolved from apes who are social animals. No matter what we achieve materially, we will always crave social recognition, status, and love from other humans. And because other humans are imperfect, we can never get to a state where we are perfectly loved, content, and free from the fear that these things will be taken away."
He has a similar argument in "Mere Christianity", where (I paraphrase and over-simplify) he says that whatever goodness there is in humans proves there must be a God, because otherwise why would people ever want to do anything "good" rather than just what immediately benefits them? But I feel like that has a similar response to the above - we know that evolution exists, we know we evolved from apes, and we've watched apes exhibit the same social behaviors that we do. There are many times when it makes sense to act pro-socially (to do "good" things as CS Lewis would describe them) in order to get a greater benefit (from your community) than you would by acting purely selfishly.
This doesn't make humans bad, or make it any less "good" to do good things! I don't understand the idea that these behaviors are any less good or meaningful because we do them for natural reasons rather than supernatural ones.