Mark 9:48-49
For in hell the worm of those who are there will never die [i.e., their gnawing punishment will never cease] and the fire [there] will never go out.
Hebrews 6:4-8
[These are people] who were once enlightened [by the Gospel message], who had experienced the gift from heaven [i.e., forgiveness, never ending life, etc. See Rom. 6:23], who had partaken of the Holy Spirit [See Acts 2:38],
Hebrews 10:26-31
For if we go on sinning intentionally, after we have received the full knowledge of the truth, there is no longer any sacrifice for [our] sins.
2 Peter 2:19-22
[Although] these people promise "liberty," they themselves are slaves to corrupting influences, for people are slaves to whatever controls them.
Revelation 21:8
But the place for cowards, and unbelievers, and disgusting people [i.e., because of their terrible sins], and murderers, and sexually immoral people, and sorcerers, and idolaters, and all liars, will be the lake that burns with fire and sulphur. This is the second death."
Revelation 22:11
The person who is doing wrong should continue to do wrong [if he wants to]; and the person who is [morally] filthy should continue to be [morally] filthy [if he wants to]; and the person who does what is right should continue to do right [if he wants to]; and the person who is living a holy life should continue to live holy [if he wants to]."