ANSWER: The doctrine of the eternal existence of the wicked is found in all those passages which speak of their endless punishment in plain terms, as in Matt. 25:46, or under the imagery of "unquenchable fire" (Matt. 8:12). "Smoke of their torment ascending forever and ever" (Rev. 14:11); "the false prophet tormented day and night forever and ever" (Rev. 20:10); "eternal sin" (Mark 8:29, Revision); "eternal fire" (Matt. 25:41). There is no Scripture in proof that repentance after death is possible. The idea that God will ever annihilate a free moral agent is nowhere found in the Bible. If that is the way to secure a holy universe, God would have annihilated the devil long ago.
— Steele's Answers p. 171, 172.