"Over the years, this film's reputation has grown enormously, and its cult status must be as high as any horror movie. Richard Matheson, who scripted it, was able to improve immeasurably on Dennis Wheatley's ponderous novel, and it is consequently the best film that Fisher and Hammer ever made, an almost perfect example of the kind of thing that can happen when melodrama is achieved so completely and so imaginatively that it ceases to be melodrama at all and becomes a full-scale allegorical vision. Christopher Lee has never been better than as the grim opponent of Satanism, and the night in the pentacle during which the forces of evil mobilise an epic series of cinematic temptations rediscovers aspects of mythology which the cinema had completely overlooked." - Time Out