This study examines the twin theories of coinherence and substitution that Williams developed in his seven novels. The theories are mystical and theological in their development. Williams was deeply influenced by The Inklings, the literary group which he belonged to while he was with the Oxford University Press during WW II. I have used C.G. Jung's ideas about religion as well as Soren Kierkegaard's view of Christian existentialism. The study presents Williams' life, in brief, his work at Oxford UP; his intellectual development. There are two chapters devoted to a close examination of each novel and its relationship to his theories, and a chapter which reviews the existing Williams criticism. The final chapter is a conclusion for the work.