Hell in the bible is not called hell for a reason. Jesus uses words like Gehenna (a physical location of a garbage dump that was always on fire because of the amount of garbage being poured into it) or Hades/Tartarus (concepts people at the time would have understood as a hole in the ground). Our concept of hell came along because of Dante's Divine trilogy which was a work of fiction based loosely in Christian theology discussing his way through "hell" on his journey to be united with his waifu. The generally accepted "theory" among Christians who don't believe in hell for the above reasons is that the fiery inferno either refers to the literal garbage dump where the bodies of criminals and sinners were dumped, or to god's greatness burning sinners into nonexistence when the kingdom of heaven comes to earth, since you are not "spiritually" dead but have merely experienced a physical death until the day of judgement. The "torment" such souls feel is because they see god and heaven (the singularity), but are unable to be part of it because of their refusal to accept god and Christ due to their sins in physical life.
If you come at it from this angle then of course there is potential salvation for those in hell, but the issue is that one who refused to embrace god in life and sinned as a result of it has an impure soul that will not allow them to become part of the singularity since the sins of life act as metaphorical shackles in death to one's mortal coil. To keep up with the metaphor, everyone sins and the difference is whether those shackles are thin threads or loose ropes that can be let go of with enough strength/acceptance (vices, ties to the material, minor sins, agnosticism, etc.), or if those shackles are iron chains welded to the ground (major sins like suicide, murder, atheism, etc.). One shouldn't fear the concept of hell since people aren't "suffering torture at the hands of devils and demons" but rather they should fear hell because they should want eternal life for everyone and for nobody to cease to exist after judgement day. Those who sin deeply simply wish to cease to exist after they leave their mortal coil and "temporarily suffer" upon learning what they have lost in doing so.
The way my priest explained it to me growing up was not in fire and brimstone, but in a mountain of sand.
>Imagine you are given the impossible task of transferring a mountain of sand from point A to point B one grain at a time
>You are always climbing to the top of the first pile to grab a grain of sand and placing the new grain at the top of the new sand pile you are making.
>The task never becomes more laborious than it does, but this continues for seemingly forever
>When you are finally finished with moving each and every grain of sand, you are instructed to now put every piece of sand one by one back in its original place
>Some days you laugh, some days you cry, some days you feel like you cannot take it any more but you must continue as you never tire completely
>Even if you complete this task, you must repeat the original task again, back and forth waiting until the day of judgement when you are finally able to rest
>This, is hell