Furnace

Furnaces in Scripture served both industrial and symbolic purposes. Industrially, smelting furnaces (Hebrew kur) were used for refining metals — gold, silver, and copper — and the image of purifying metal in a furnace became one of the most powerful metaphors in Scripture for God's refining work on his people: "I have refined thee, but not with silver; I have chosen thee in the furnace of affliction" (Isaiah 48:10; Proverbs 17:3; Malachi 3:2–3). Egypt itself is called the "iron furnace" in Deuteronomy 4:20 and 1 Kings 8:51, expressing the severity of Israel's bondage.

The Chaldean furnace (attun) of Daniel 3 was a large industrial furnace with a wide open mouth at the top, into which Shadrach, Meshach, and Abednego were thrown for refusing to worship Nebuchadnezzar's golden image. The narrative of their miraculous preservation — with a fourth figure "like the Son of God" walking in the flames with them (Daniel 3:25) — became a touchstone of faith in divine deliverance under persecution. In the New Testament, the furnace of fire appears as an image of eschatological judgment (Matthew 13:42, 50). Genesis 19:28 describes the smoke of Sodom rising like the smoke of a furnace after its destruction.