Belial
Archimandrite Nikifor’s Biblical Encyclopedia
(worthless, good-for-nothing; a Hebrew word) — a word frequently found in the Old Testament, occurring first in the Book of Deuteronomy (13:13), then in Ps. 41 [40]:9 [8], Judg. 19:22, 1 Sam. 1:13, and elsewhere; in the New Testament it occurs only in the Second Epistle of the Apostle Paul to the Corinthians (6:15), where it is read “Belial.” In general this word is applied by the sacred writers to all depraved, impious, and evil people, but especially to Satan, as the chief author of all impiety and evil.
For this reason the question of the Apostle Paul, addressed to the citizens of the city of Corinth, who were known, as is well known, for their looseness and levity of morals, appears especially forceful: “And what concord hath Christ with Belial? or what part hath he that believeth with an infidel?” (2 Cor. 6:15).