Matt. 3:12; Luke 3:17 - John the Baptist said the Lord will burn the chaff with unquenchable fire. This unquenchable fire is the state of eternal separation from God, which the Church has called "hell" for 2,000 years. Some Protestant communities no longer acknowledge the reality of hell.
Matt. 25:41 - Jesus says, "Depart from me, you cursed, into the eternal fire prepared for the devil and his angels."
Matt. 25:46 - Jesus says, "they will go away into eternal punishment" which is in reference to this eternal fire.
Mark 9:47-48 - Jesus refers to hell as where the worm does not die and the fire is not quenched. It lasts forever.
2 Thess. 1:6-9 - the angels will come with flaming fire and the disobedient will suffer punishment of eternal destruction. It is important to note that "destruction" does not mean "annihilation," as some Protestant denominations teach. It means eternal exclusion from the presence of God.
Jude 6-7 - the rebelling angels, and Sodom and Gomorrah, serve as an example by undergoing a punishment of eternal fire.
Rev. 14:11 - the worshipers of the beast suffer and the smoke of their torment goes up for ever and ever.
Rev. 20:10 - they're tormented in the lake of fire and brimstone day and night forever and ever.
Isaiah 33:14 - "Who of us can dwell in the everlasting fire?" This is a reference to hell which is forever.
Isaiah 66:24 - their worm shall not die and their fire shall not be quenched. We cannot fathom the pain of this eternal separation from God.
Jer. 15:14 - in my anger a fire is kindled which shall burn forever. Hell is the proper compliment to the eternal bliss of heaven.
Judith 16:17 - in the day of judgment the Lord will take vengeance on the wicked and they shall weep in pain forever. Hell is a place that sinners have prepared for themselves by rejecting God, who desires all people to be saved in His Son Jesus Christ. God sends no one to hell.
-Scripture Catholic