What I really meant is, in Planescape setting for instance, characters can easily travel to the hells via dimensional planes. I was just brainstorming how would morality and religions function in a world where you could actually visit the places you will potentially spend time after death, while you are alive.
Arguably, each of the characters in Planescape: Torment are actually on their own personal journey through hell for the entirety of the game. Indeed, the game ends when the protagonist decides on his final punishment (or, if you're so inclined, redemption).
For example in real life, since it is not 100% for sure after-life exists, the only factors restraining people from committing *evil actions* (yes, very subjective in some cases) are things such as the laws, their conscience and beliefs. I am sure people would think a second time before committing crimes etc. if it was a common fact that after-life existed and you would be punished in hell for sure (even if you were able to get away with it in real life).
I think you get the point. Sorry, if this philosophical aspect had already been covered on the forums, but this has been one of the questions which started bothering me especially while I was playing PS:T. It certainly decreases the realism of any setting IMHO and lawful evil (smart evil) characters don't seem to make much sense in such settings. (Only if they pursue immortality to avoid their fate or try to redeem themselves in order to go to the neutral or good heavens)
Well, the thing is that your question really is founded on the presumption of the existence of an objective moral standard that applies to everyone. So the question is not whether or not hell exists. But in truth whether or not there is such a thing as a judging, all-knowing omnipresence. Or alternatively whether people actually only go to hell if they feel themselves that they deserve it.
Putting aside the crisis of faith for a moment, though -- lawful evil characters that are not cartoon villains can certainly make sense even if they believe in a hell with eternal fire and damnation. In two ways, actually. Either the characters eventually realize themselves that their actions are deserving of retribution. In which case lawful evil makes complete sense. They now not only justify themselves in the afterlife but also in the life they have come to live. Because there is a logical consequence to their behaviour: When I do evil things, I will pay for this in the afterlife. And this justifies the deeds the character will do to, for example, survive or live well in this life.
The other way is that the character justifies evil acts as part of the natural order of things, for example. They don't see the suffering of other people as something to avoid. They would perhaps live by the idea that the strong rule over the weak. And that there's no reason to complain if someone fights and kills you. That they then learn to revel in torturing others. Or destroying entire communities that might become a threat one day, or let some live to make sure that they will have a chance to take revenge and wage war on you in the future. Etc. That won't make the character committed to a neutral morality, but a very strict moral compass that ultimately justifies even the most heinous act.
In either case, the character actually believes in evil in certain ways. They know what suffering and hate is. But they justify and commit to the existence of it anyway.
Aside from that, all the D&D universes have various misguided sects and gods that lead on their followers to commit an array of acts, with a very thorough moral justification, that would mark them as dedicated and lawful evil. For all kinds of solid local justifications ranging from uncelestial godly rewards, to tortured guilt creating the framework for the servants unwillingly committing to evil as a concept, etc.
"Let he who is without sin cast the first stone."
That's the new testament. Which hardly works without a subjective interpretation of what evil is. Where very likely people would only go to hell if they themselves believe they are deserving of it. Obviously the form of punishment would be subjectively decided as well.
Essentially, the concept of "lawful evil" has been very predictably interpreted into d&d to mean that the character acts with evil intent as a rule. That they seek to be traitorous, to stab people in the back at every possible opportunity, that they have no moral conscience, etc. But that's not the case.
What happens is that all the gods in the fantasy universe might intervene while the characters are still alive, and the alignments actually reflect you as a person. A paladin can commit "objectively" atrocious acts, but believe it's done in the service of good. And as such be a lawfully good person who genuinely tries to commit to good as a concept. And so won't actually fall from grace until they believe themselves that they have irreversibly tainted their soul in their blind zeal. At which point the gods and powers that be actually will instantly answer to the fact that the paladin now believe themselves to be evil.