Charles Spurgeon Commentary Matthew 13:49-50

"So shall it be in the end of the world: the angels shall come forth, and sever the wicked from among the righteous, and shall cast them into the furnace of fire: there shall be the weeping and the gnashing of teeth." — Matthew 13:49-50 (ASV)

The separation between “the wicked” and “the just,” who are in the kingdom, will be at the close of the dispensation. It will be accomplished by the messengers of God, the appointed angels. It will be done infallibly, readily, fully, and finally.

The doom of the wicked is described in terms which are terrible to the utmost degree. Those who would have us think lightly of the punishment of the ungodly find no support in the teachings of the Lord Jesus. Neither does the idea that fire causes annihilation find any support from the metaphor used here, for in the furnace of fire there shall be wailing and gnashing of teeth.

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.

Not fire, then, which annihilates, but fire which leaves in pain and causes weeping and gnashing of teeth.