In Solution of the Great Problem, Abbé Delloue defines the “great problem” to be the fate of the soul’s existence after death. Delloue outlines various solutions that have been provided throughout history—particularly by materialism and pantheism. He then provides the Christian argument for God, dividing the argument into three parts: popular, scientific, and philosophical. From there, Delloue sets the stage for the Catholic teaching of the doctrine of immortality.