What does Daniel 3:22 mean?

The furnace used here was probably a lime kiln: a large earthen dome with an open top to insert fuel and a hole on the side to remove waste. In his intense rage, King Nebuchadnezzar had ordered it superheated for an execution (Daniel 3:16–19). Strong men were commanded to tie up three Hebrew captives (Daniel 1:6–7) and throw them into this furnace immediately. This urgency contributed to the deaths of these executioners (Daniel 3:20–21). To respond so quickly, they may have neglected to put on protective clothing. They likely had no time to arrange a careful way to put the victims into the top of the furnace.

These were respected soldiers in the army of Babylon, previously referred to with the term "mighty men" (Daniel 3:20). But the greatest warrior is no match for heat that can melt bronze. Nor is such a man strong enough to resist judgment by the One True God, whom these Hebrew men worshiped. Someday, during what is commonly called the "end times," all nations of the world will attempt a military coup against God, but they will not be able to withstand His judgment (Revelation 20:7–10). Psalm 2:1 asks, "Why do the nations rage and the peoples plot in vain? The kings of the earth set themselves, and the rulers take counsel together, against the Lᴏʀᴅ and against his Anointed." Psalm 2:5 says God "will speak to them in his wrath, and terrify them in his fury."

Based on the king's comments later (Daniel 3:24–25), it's not likely the soldiers fell into the furnace. More likely, they were overcome with the heat coming from the opening and died on the surface.