What is the theme in Hell House by Richard Matheson?

Good vs evil is an important theme.The very basis of mankind's survival centers around the battle of good and evil. Emeric Belasco created an atmosphere of pure evil in his house, later named Hell House, and encouraged his guests, and family members alike to partake with abandon. He had an enormous ego that required constant boosting and it was increasingly obvious that Emeric was out of his mind. He sank deeper and deeper into depravity, encouraging his guest to partake of everything from human flesh to aphrodisiacs, orchestrated orgies and even took his own sister as his mistress for over a year. Those who arrived as regular guests, unaware of his debauchery, soon became part of the house and it's games of increasing depravity.