This is the first chapter in the section that's supposed to be about what Christian's believe.
"I have been asked to tell you what Christians believe, and I am going to begin by telling you one thing that Christians do not need to believe. If you are a Christian you do not have to believe that all the other religions are simply wrong all through. If you are an atheist you do have to believe that the main point in all the religions of the whole world is simply one huge mistake. If you are a Christian, you are free to think that all those religions, even the queerest ones, contain at least some hint of the truth. When I was an atheist I had to persuade myself that most of the human race have always been wrong about the question that mattered to them most; when I became a Christian I was able to take a more liberal view."
Which is interesting. I know that there are many Christians who do believe this way, but there are many who do not. And I think there is something about Christianity, and all of the Abrahamic faiths for that matter, that assumes exclusivity. Christianity does make the claim that it is the only correct path to heaven, whether it states it explicitly or not. In recent years there has been a relaxation of this policy, with many of the Christian institutions stating that there exist aspects of grace outside of the fold of Christianity, but that has not been the historical understanding.
One of the things I found sort of telling and maybe helpful in explaining Lewis' viewpoints is his version of atheism. When Lewis was an atheist, he based his rejection of the idea of God on the fact that the world was not fair, or just. That if there was a God, and God was good, then how could He allow the world to continue in the way that it was? Rather than (at the time) understanding that free will and the fallen nature of the world is what impacts and creates the nature of the world, he decided that the unfairness of reality meant that there was no God. Okay, that was his view and he later changed it. That's fine. But Lewis seems to think that every other atheist on the planet for all time shares this same perspective and reasoning. Which I know is not true. There are many reasons that people have for being atheists.
Many, perhaps even most, weigh the evidence for a divine being against the evidence for other, less supernatural explanations for things and they find that the scales tip in the favour of a material universe, where there is no supernatural explanation for things.
Everyone's reason is their own, and it seems good to them. They might be wrong - people who believe in God or gods or the Unmoved Mover might be wrong as well. We don't really, ever, know. We work with the evidence we see, through the lense of the life that we have and we take things on faith, one way or the other. Lewis buttonholing everyone into the same thought process as he used sits badly with me.