Sentence:  It is very much to be doubted if Mervyn Hogarth had ever in his life given more than a passing thought to any black art or occult science. Certainly he was innocent of prolonged interest in, let alone any practice of, diabolism, witchcraft, <WSD>demonism</WSD>, or such cult. 
Meaning of the word marked with <WSD> tags:  Belief in, or worship of demons or devils.