Fire has multiple functions in Scripture, including well-known purposes as warmth, cooking, and destruction. In the present context, “fire” describes the (destroying) anger of God (Hosea 8:5; Nahum 1:6; Isaiah 66:15–16; Jeremiah 15:14; Ezekiel 21:31). The addition of the word “lake” underscores the size of the fire, that is, the intensity and the reach of God’s anger. It is far greater than simply a furnace (Daniel 3:6, Daniel 3:19). This is a picture of hell.
20 And the beast was captured, and with it the false prophet who in its presence had done the signs by which he deceived those who had received the mark of the beast and those who worshiped its image. These two were thrown alive into the lake of fire that burns with sulfur.