Man or Rabbit

"Man or Rabbit" ask the question can one live a good life without believing in Christianity? According to Lewis there is not really any debate about whether your can or can not. If you are a Christian you live a life for God. If you are a materialist then you live life for earthly happiness. Both can't be right. If one is right then the other is absolutely wrong. Lewis says that "If Christianity should happen to be true, then it is quite impossible that those who know this truth and those who don't to be well equipped for leading a good life. Knowledge of the facts must make a difference to ones actions. Suppose you found a man on the point of starvation and wanted to do the right thing. If you had no knowledge of medical science, you would probably give him a large solid meal; and as a result your man would die."
I think this really sums up what Lewis is trying to get across through out the whole essay. If you believe in Christianity then it is impossible for a non-christian to lead a good life even if they want to. You can have all heart and good intentions to do so, but if you are not properly equipped you will end up doing more damage then good in the long run. I don't think what Lewis is trying to say is that there is no good non-christians out there. There are plenty of people who don't believe in Christianity, but are very good people. What Lewis is trying to say that no matter how good there lives may seem in the long run it leads Hell. It does not mean they can't do good.