This book seeks to examine the mutual interplay between existentialism and Christian belief as seen through the work of three existentialist thinkers who were also committed Christians - a Spaniard (Miguel de Unamuno), a Russian (Nikolai Berdyaev), and a Frenchman (Gabriel Marcel). They are compared with each other and with leading non-religious existentialists. The major themes studied include reason, freedom, the self, belief, hope, love, suffering, and immortality.