Sentence:  It is true, that by the workings of the law of attraction, and the susceptibility of mortals to the influence of spirit powers, mortals may become obsessed by the spirits of evil—that is evil spirits of men who once lived on earth—and this <WSD>obsession</WSD> may become so complete and powerful that the living mortal may lose all power to resist this influence of the evil spirits... 
Meaning of the word marked with <WSD> tags:  Influence or control by evil spirits without possession.