Beelzebul is a slight variation of Baal-zebub, the god of Ekron mentioned in 2 Kings 1:2–6 and 2 Kings 1:16. Satan himself was considered to be at work in Baal worship and as a result, this name came to be used in Jewish communities to refer to anything demonic and later to the prince of demons
himself. The Bible certainly identifies the worship of idols, such as the god of Ekron, with the demonic (see Deuteronomy 32:17, Psalm 106:37–38, Leviticus 17:7).
22 And the scribes who came down from Jerusalem were saying, “He is possessed by Beelzebul,” and “by the prince of demons he casts out the demons.”