What is the theme in Hell House by Richard Matheson?

Faith vs science is another theme in the book. In the final excursion to Hell House, one scientist, his wife, a spiritualist and a medium spend a week trying to determine once and for all the source of the hauntings in the home. They are there at the direction of Rolf Deutsch who is dying, and wants the answers, one way or another, before he takes leave of his mortal self. Dr. Lionel Barrett is a renowned scientist who is absolutely convinced that all hauntings and associated problems are created by the residual electromagnetic forces left behind. He describes them as auras and builds a machine he calls the Reversor which he claims will counteract any energy that is left in the house.