2Co 6:15 What harmony exists between the Messiah and Beliar, or what do a believer and an unbeliever have in common?
"Belial aka Beliar" is a Hebrew word meaning something like "worthlessness one":
בְּלִיַּעַל belı̂ya‛al bel-e-yah'-al From H1097 and H3276; without profit, worthlessness; by extension destruction, wickedness (often in connection with H376, H802, H1121, etc.): - Belial, evil, naughty, ungodly (men), wicked. Total KJV occurrences: 27
†בְּלִיַּ֫עַל S1100 TWOT246g GK117527 n.[m.] worthlessness (cpd. בְּלִי not, without and יַעַל worth, use, profit)—בּ׳ Dt 13:14 + 20 times; בְּלִיָּ֑עַל ψ 101:3 + 5 times;—the quality of being useless, good for nothing. 1. abstr. אִישׁ (ה)בליעל, אַנְשֵׁי הבליעל, worthless, good-for-nothing, base fellows 1 S 25:25; 2 S 16:7; 20:1; 1 K 21:13; Pr 16:27; = בֶּן־ב׳ 1 S 25:17, בְּנֵי ב׳ Dt 13:14; Ju 19:22; 20:13; 1 S 2:12; 10:27; 1 K 21:10, 13; 2 Ch 13:7; בַּת ב׳ 1 S 1:16 (drunken woman); עֵד ב׳ base witness Pr 19:28; דְּבַר ב׳ base, wicked thing ψ 41:9 (yet cf. 3 infr.), 101:3 (add prob. also 1 S 29:10, so 𝔊 We Dr); דָּבָר … ב׳ (elliptical and in apposition) Dt 15:9. 2. concr. elliptical of אישׁ ב׳ 2 S 23:6 Jb 34:18; כָּל־אִישׁ רַע וּבְלִיַּעַל 1 S 30:22; אָדָם בְּלִיַּעַל Pr 6:12. 3. ruin, destruction: so ψ 41:9 according to De Che al., but v. supr.; יֹעֵץ ב׳ counsellor of ruin Na 1:11; ב׳ alone a man of ruin, destroyer Na 2:1; נַחֲלֵי ב׳ floods of destruction (|| שְׁאוֹל) 2 S 22:5 = ψ 18:5.
Brown, F., Driver, S. R., & Briggs, C. A. (1977). Enhanced Brown-Driver-Briggs Hebrew and English Lexicon (p. 116). Oxford: Clarendon Press.
The LXX translates it with παρανομοι:
Deu 13:13 Certain men, the children of Belial, are gone out from among you, and have withdrawn the inhabitants of their city, saying, Let us go and serve other gods, which ye have not known;
(Brenton) (Deut 13:13) Evil men have gone out from you, and have caused > >all the inhabitants of their land to fall away, saying, Let us go and worship other gods, whom ye knew not,
(LXX) (Deut 13:13) Ἐξήλθοσαν ἄνδρες παράνομοι ἐξ ὑμῶν καὶ ἀπέστησαν πάντας τοὺς κατοικοῦντας τὴν πόλιν αὐτῶν λέγοντες Πορευθῶμεν καὶ λατρεύσωμεν θεοῖς ἑτέροις, οὓς οὐκ ᾔδειτε,
Paul seems to allude to this passage in 2 Thess 2:
2Th 2:3 Do not let anyone deceive you in any way, for it will not come unless the rebellion [ἀποστασία, "falling away"] takes place first and the man of sin, who is destined for destruction, is revealed. 2Th 2:4 He opposes and exalts himself above every so-called god and object of worship. As a result, he seats himself in the sanctuary of God and himself declares that he is God.
Modern OTs do not treat Belial as a proper name but rather as a common noun but Paul transliterates Belial as a name.
Does Paul consider the "man of sin" to be a person named "Belial"?