Furnace of Fire

The Son of man shall send forth his angels, and they shall gather out of his kingdom all things that offend, and them which do iniquity; And shall cast them into a furnace of fire: there shall be wailing and gnashing of teeth. Matt. 13:41-42

So shall it be at the end of the world: the angels shall come forth, and sever the wicked from among the just, And shall cast them into the furnace of fire: there shall be wailing and gnashing of teeth. Matt. 13:49-50

Why so much anguish? Cos their suffering is real. The reason they will be wailing and grinding their teeth is bcos they will be cast into a real furnace of fire. Their reaction is no different than that of any person on earth if they were caught hold of and cast into a furnace of fire.