In my religious background, there is huge emphasis on fearing God, fearing His wrath, and hell. Hell is very graphical. Here are some verses showing how graphical it is:
"And if ye do it not - and ye can never do it - then guard yourselves against the Fire prepared for disbelievers, whose fuel is of men and stones." (Q 2:24) "Lo! Those who disbelieve Our revelations, We shall expose them to the Fire. As often as their skins are consumed We shall exchange them for fresh skins that they may taste the torment. Lo! Allah is ever Mighty, Wise." (Q 4:56) "For such, their habitation will be hell, and they will find no refuge therefrom" (Q 4:121) "Lo! the hypocrites (will be) in the lowest deep of the Fire, and thou wilt find no helper for them;" (Q 4:145) "Lo! those who disbelieve and deal in wrong, Allah will never forgive them, neither will He guide them unto a road, Except the road of hell, wherein they will abide for ever. And that is ever easy for Allah." (Q 4:168-169) "They will wish to come forth from the Fire, but they will not come forth from it. Theirs will be a lasting doom." (Q 5:37) "Theirs will be a bed of hell, and over them coverings (of hell). Thus do We requite wrong-doers." (Q 7:41) "O ye who believe! Lo! many of the (Jewish) rabbis and the (Christian) monks devour the wealth of mankind wantonly and debar (men) from the way of Allah. They who hoard up gold and silver and spend it not in the way of Allah, unto them give tidings (O Muhammad) of a painful doom, On the day when it will (all) be heated in the fire of hell, and their foreheads and their flanks and their backs will be branded therewith (and it will be said unto them): Here is that which ye hoarded for yourselves. Now taste of what ye used to hoard." (Q 9:35) "Know they not that whoso opposeth Allah and His messenger, his verily is fire of hell, to abide therein ? That is the extreme abasement." (Q 9:63) "Hell is before him, and he is made to drink a festering water, Which he sippeth but can hardly swallow, and death cometh unto him from every side while yet he cannot die, and before him is a harsh doom." (Q 14:16-17)
Even though I have left this religion but I get this nightmare that I am getting punishment for leaving the religion. I feel scared that what if I am wrong and end up burning in hellfire.
How to get rid of this fear so that I can live my life freely?
The naive idea of Hell (no pun intended) is on its face absurd. We know that cognition and sensation come from physical processes (the brain, body and nervous system) from observing how these things fail and what happens. As such, the idea of an eternal fire that burns you without the escape of death is impossible: even if the nerves that sense the agony of their own destruction were magically regenerated, the nervous system would shut down.
Theologians dealing with people who saw through this acknowledged it and reframed Hell as something more philosophical: the absence of the presence of God and such, with the assumption that knowing that the big man in the sky loves you is the one thing that makes life worth living. This assumption has also been refuted: Existentialist philosophy, for example, makes short shrift of it: yes, there is no God, no grand narrative, and no ultimate universal meaning to our lives, so why bother living? Because we make our own meaning as we interact with others and engage with the world. No existentialist would fear this Hell if it existed, because they’d be making their own fun in the cold, unhallowed darkness.
Also, if Satan is the bad guy, why is he working as the good guy’s jailer and torturing those who were insufficiently respectful to him? That part makes no sense.
I personally love Satan. If you read the conversation between God and Satan in the scripture that I quoted, you will feel that it is a hero. Regarding hell, some scholars in my previous religion like Ibn e Arabi and Ibn e Taymiyah have said though that hell will end at some point and all the dwellers in hell too will be annihilated (it was and is very fringe opinion though)