C.S. Lewis wrote "The Chronicles of Narnia" as fantasy novels for children. Written between 1949 and 1954, the series is Lewis's most popular work. The books contain Christian ideas intended to be easily accessible to young readers. In addition, Lewis used characters from Greek and Roman mythology as well as traditional British and Irish fairy tales.
According to the paper,"The Wardrobe as Christian Metaphor", by Don W. King, Mythlore 14 (Autumn 1987), C.S. Lewis is aware of how frequently the door is used metaphorically in the New Testament and that Jesus is often associated with a door. In John 14:6 for instance, Jesus tells to be the door to communion with God. Lewis' knowledge of Scriptures is put to work throughout Narnia. As we can read in the paper by Don W. King, "doors are used significantly in the stories and echoes of the Biblical references made above resonate clearly. Four specific points about Lewis' use of doors are noteworthy: 1) Literal doors lead to the Door, Aslan; 2) Aslan is a two-way door; 3) Passage through the different literal doors into Narnia is always unplanned; and 4) All who enter the doors are called into Narnia, but none are compelled to stay; indeed, some who are called do not seem to belong. First, in every instance the literal doors that the children use to enter Narnia eventually lead directly to the Door, Aslan. The doors themselves take on different forms, from the wardrobe door in The Lion, the Witch and the Wardrobe to the framed picture in The Voyage of the Dawn Treader to the railway station in Prince Caspian and The Last Battle to the magic rings and the Wood Between the Worlds in The Magician's Nephew. Literally, the doors function to take the children out of their real world and into a new other world". The doors serve to move the children from the everyday life to a new reality. All the doors inexorably lead to Aslan.