Belial is the Anglicized form of the Hebrew b’li-ya’al, from b’li, “not,” and ya’al, “worth, profit.”
Thus the original sense of belial was merely “unprofitable.”
From this sense, though, the term Belial came to have the meaning of “wickedness,” and the many references in the Old Testament to a “son of Belial,” “daughter of Belial,” etc., refer to someone who is very wicked.
Later, Belial, although never previously a proper name, became used as one of the names of the devil, the personification of all wickedness, so that now the phrase “son of Belial” is most often taken to be synonymous with “spawn of Satan.”
