I read them all as a child, and saw the Christian allegory in LWW and Last Battle, but not the others. I grew up in a Quaker family, but without a lot of Christian input (except via Children's Class on Sundays when they often tried to read a bible story to us and get us to draw pictures of - which I ignored as I didn't want to draw things and mostly sat in a corner and read whatever I was reading).
I enjoyed the books, especially Horse and His Boy and Prince Caspian, but stopped reading them around 7/8 deciding that I'd grown out of them, and I don't think I reread them until around when the first film came out. It was very interesting to go back to them and see so much more of the messages and allegories.