Hellfire: What did Jesus mean by Gehenna, and what is the "second death"?

"Hell" in English translates three different words: Sheol (the grave), Hades (same), and Gehenna (Valley of Hinnom — a garbage dump outside Jerusalem). Key texts: Ecclesiastes 9:5 (dead know nothing), Romans 6:23 (wages of sin = death, not torment), Revelation 20:14 (lake of fire = the second death), Jeremiah 7:31 (burning humans "had not come up into God's heart"). Mark 9:48 quotes Isaiah 66:24 — the context in Isaiah is dead bodies being consumed, not living people in torment. Does the Bible consistently teach death as unconscious non-existence rather than torment? nwtprogress.com