The Philistine word, Baal, meaning Lord, is the root of the title Beelzebub, meaning Lord of the flies. A few evolutions later, Beelzebub becomes interchangeable with Satan.
The video above explains who ‘the flies’ are. I will include no remark now. The film is clear and has punch. I do not want to confound your experience with my ideas. Apostate that I am. I remain intrigued by the Biblical parallels. If the mission is to reveal the depth of evil, the film is more compelling than I could be.