Watch where esh first appears, because the first appearance sets the semantic core. It is not Sodom. It is the covenant of the pieces: a smoking fire pot and a flaming torch passing between the divided sacrifice while Avram sleeps (Genesis 15:17). The first fire in Scripture is YHWH Himself walking the blood path of a covenant, taking the obligation onto Himself. Fire's founding meaning is covenant presence, the nearness that both binds and consumes.

The rest of the Tanakh keeps that thread. The bush burns and is not consumed while a covenant rescue is announced (Exodus 3:2). The refiner sits over the fire in Malachi 3, not to destroy the sons of Levi but to purge them until their offering is right. So when Yochanan the Immerser announces One who will immerse in Ruach and esh (Luke 3:16), the Hebrew ear does not hear a threat bolted onto a blessing, Spirit for the good and fire for the wicked. It hears one promise with two faces: the covenant presence of HaShem surrounding a person completely, cleansing what it touches so the person can serve. Fire is what covenant nearness feels like to whatever in us cannot survive it.