The Catholic Encyclopedia
This sense is derived from 2 Corinthians 6:15, where Belial (or Beliar) as prince of darkness is contrasted with Christ, the light. It is clear in the Vulgate and Douay translations of 1 Kings 21:10 and 13, where the same Hebrew is rendered once as Belial and twice as "the devil".
In the other instances, too, the translators understood it as a name for the prince of evil, and so it has passed into English. Milton, however, distinguishes Belial from Satan, regarding him as the demon of impurity. In the Hebrew Bible, nevertheless, the word is not a proper name, but a common noun usually signifying "wickedness" or "extreme wickedness". Thus, Moore renders "sons of Belial" as "vile scoundrels" (Judges 19:22); most prefer "worthless fellows".
In some cases belial seems to mean "destruction", "ruin"; thus in Psalm 12:9, the word is parallel to the thought of utter destruction and seems to mean the same. In Psalm 18:5, it is parallel to "death" and "Sheol"; some understand it as "destruction", Cheyne as "the abyss".
The etymology of the word is doubtful; it is usually taken to be a compound meaning "worthlessness." Cheyne suggest an alternate that means "that from which no one comes up", namely the abyss, Sheol. St. Jerome's etymology "without yoke", which he has even inserted as a gloss in the text of Judges 19:22, is contrary to Hebrew philology.
Belial, from meaning wickedness or Sheol, could develop into a name for the prince of evil or of darkness; and as such was widely used at the beginning of our era. Under the names Beliar, Berial, he plays a very important rôle in apocryphal literature, in the "Ascension of Isaias", the "Sibylline Oracles", and the "Testament of the Twelve Patriarchs". He is the prince of this world and will come as Antichrist; his name is sometimes given also to Nero, returning as Antichrist.
CHEYNE in Encyc. Bib. (New York, 1899); MOORE, Commentary on Judges (New York, 1900), 419; GARVIE in HAST., Dict. of Bible (New York, 1903); DEANE, Pseudepigrapha (Edinburgh, 1891); LESÊTRE in VIG., Dict. de la Bible (Paris, 1894); CHARLES, Ascension of Isaiah (London, 1900); CHARLES, Eschatology, Hebrew, Jewish, and Christian (London, 1899).
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Obstat, Nihil. Lafort, Remy, Censor. Entry for 'Belial'. The Catholic Encyclopedia. https://www.studylight.org/encyclopedias/eng/tce/b/belial.html. Robert Appleton Company. New York. 1914.