John Wyndham (John Wyndham Parkes Lucas Beynon Harris, in full) fought in World War II, an experience shared by many and which made many give prolonged contemplation to the destruction of the world. Wyndham used The Chysalids, as well as his other novels, especially The Day of the Triffids (you might like that one...) and The Kraken Wakes to explore the role of human logic in surviving worldwide catastrophe. His conclusion, illustrated in The Chrysalids, is that in the face of disaster, humankind's dependence on the logic of the present order--the "how things are and have always been and will continue to be"--is a hindrance that works to humanity's detriment.
However, a glimmer of hope comes when humanity steps outside the logic of the established order and sees things anew, thus giving humanity another chance fo reaching its potential. In The Chrysalids, this glimmer comes in the kids who can communicate telepathically and in the large group of telepaths in Sealand, who all dared to think outside the logic of the established order and create a new order of thought that was responsive to the altered state of the planet, altered due to some cataclysmic event. In summary, Wyndham wrote to inspire readers to think beyond the accepted logic and find new ways of perceiving and reacting (What is some of your accepted logic?).