C. S. Lewis pushed people to make a decision about who they say Jesus is. And he showed that thinking of Jesus as merely a good teacher or a great human example is nonsense. Given what Jesus claimed about himself, we must say that he was either a liar, a lunatic, or truly the Lord of all.
Mark used the same logic in his gospel long before Lewis's eloquent argument. Either Jesus is nuts, demon-possessed, or the Son of God. Who do you say he is?