Have you ever wondered why Paul the apostle equate worshipping idols or eating foods sacrificed to idols as worshipping demons in 1 Cor 10:19-21? What am I saying then? That an idol is anything, or what is offered to idols is anything? 20 Rather, that the things which the Gentiles sacrifice they sacrifice to demons and not to God, and I do not want you to have fellowship with demons. 21 You cannot drink the cup of the Lord and the cup of demons; you cannot partake of the Lord's table and of the table of demons. Knowing both the MT and LXX of Psalm 96:5 (LXX 95:5) may provide a clue to Paul's argument. The MT of Psalm 96:5 reads, "all the gods of the nations are idols" while in the OG or LXX translation the reading is "all the gods of the nations are demons".
Hence, if Paul knew both the Hebrew and Greek texts of this Psalm it is likely for Paul to draw the conclusion as the LXX translators did that the idols are not just nothing or nothingness (Hebrew, ali'l vanity), but in reality these gods/idols are demonic and hence any worship proffered to the idols or eating foods sacrificed to the idols is worshipping or participating in the demonic realm which is prohibited of Christians who worship God or participate in Christ.