Some believe that the fires of hell are symbolic and/or temporal. But the following verses show that they are not.
Matt. 3:12 says, "And His winnowing fork is in His hand, and He will thoroughly clear His threshing floor; and He will gather His wheat into the barn, but He will burn up the chaff with unquenchable fire." (See also Luke 3:17.)
Mark 9:43 says, "And if your hand causes you to stumble, cut it off; it is better for you to enter life crippled, than having your two hands, to go into hell, into the unquenchable fire."
The word "unquenchable" is
asbestos in the Greek. According to the enhanced Strong's lexicon, it means "unquenchable, the eternal hell fire to punish the damned."
The following citations are from Greek dictionaries and Lexicons. They show that the word "unquenchable," which is asbestos in the Greek, (which occurs only in Matt. 3:12, Luke 3:17, and Mark 9:43) means unquenchable, without end.
"unquenchable, inextinguishable"2
"not quenched"3
"pertaining to a fire that cannot be put out" - "unquenchable."4
"unquenched, unquenchable"5
"that cannot be put out"6
"inextinguishable"7
Is hell eternal? Yes it is.
Are its fires without end? Yes they are.
Is it a pleasant doctrine to discuss? Not really.
But, hell is real. This is all the more reason to preach the gospel. Jesus said,
"And if your hand or your foot causes you to stumble, cut it off and throw it from you; it is better for you to enter life crippled or lame, than having two hands or two feet, to be cast into the eternal fire," (Matt. 18:8).
https://carm.org/hell-eternal