Did the Septuagint change what the Bible says about demons?

Yes, and the shift was consequential enough that it shaped New Testament theology.

The clearest example is Psalm 96:5. The Hebrew text reads: "All the gods of the peoples are elilim" -- the word elilim (אֱלִילִים) means "worthless things, nothings." It's related to a word meaning "good for nothing" and sits in the same family as hevel (הֶבֶל, "vapor, vanity"). The Hebrew is dismissive. Pagan gods aren't dangerous -- they're empty.

The Greek translators rendered that same verse as: "All the gods of the nations are daimonia" -- demons. What the Hebrew dismissed as nothing, the Greek declared actively hostile. An "idol of no value" became a malevolent spiritual agent. That's not a translation; it's a theological upgrade.

The pattern held across multiple passages:

• The "goat-demons" (sa'ir, שָׂעִיר) of Isaiah's desolation oracles became daimonia
• The abstract "destruction" (qeteb, קֶטֶב) of Psalm 91:6 became the "noonday demon" -- a personified figure that would become a fixture of later theology
• In Isaiah 65:3, the translators inserted daimonia where the Hebrew had no demon term at all -- the Hebrew describes idolatrous rituals; the Greek names demonic recipients

Why does this matter? Because the New Testament authors read and quoted the Greek Old Testament. When Paul writes to the Corinthians about pagan sacrifice, he draws directly on the Septuagint's rendering of Deuteronomy 32:17:

"What the Gentiles sacrifice, they sacrifice to demons and not to God." -- 1 Corinthians 10:20

Paul isn't inventing the idea that pagan worship involves demons. He received it from the Septuagint -- a translation choice made centuries before his letter. The Greek-speaking Jewish world had a demon-saturated Scripture that its Hebrew-speaking ancestors would not have recognized.

This doesn't mean the translators were wrong. Paul treated the Greek rendering as authoritative, and 1 Corinthians is canonical Scripture. But understanding where the category came from -- that it was shaped by specific translation decisions at identifiable verses -- grounds the theology in a traceable textual history rather than leaving it floating as an unexplained shift.

For the full table of translation shifts and their downstream effects, see the study "Between the Testaments" -- From Silence to Storm.