Why is Narnia more than a children's series?

[Lilygloves]

(I hope this is the right place to start this topic and if there already is a topic, I am sorry. I couldn't find one like this so I figured I would start this.)
I am a huge Narnia fan (obviously), but one of the problems is that people often think that it's just a Children's series. I have met people who think that and I was just wondering if you guys could post reasons as to why Narnia is more than that. This is as much for me to defend Narnia as anyone (so I'm not just looking for points to argue), and it's interesting to think about.

[StarAsterisk]

To quote C.S. Lewis himself,

"No book is really worth reading at the age of ten which is not equally – and often far more – worth reading at the age of fifty and beyond."
— C.S. Lewis (SOOO true!)

"Those of us who are blamed when old for reading childish books were blamed when children for reading books too old for us"
— C.S. Lewis (Wow so true of me! Although I'm not old yet...)

[Louloudi the Centaur]

The books just have so much depth and themes that young children would even understand. Every time that I read the books, I feel more emotion and understanding of certain things.

[Lilygloves]

Thanks, I really appreciate this. I feel as though I'm not only reading a fantastic story, but also insight into the Bible. It seems a bit more than a children's story. It doesn't have illustrations on every page and has difficult words, so it's not even a children's series, in my opinion.