Universal salvation, the belief that all humans is saved in the end makes no sense without reincarnation
Because if hell is temporary and reincarnation is false then there is no true justice. And many people may think that their actions does not matter since they only will suffer temporary in hell
Any thoughts?
This is how I understand it. The length of time in the temporary hell, and the experience while there is determined by what a person does in their life. And of course, there are certain transgressions which render a complete disconnect to any afterlife.
In addition to this, during each person's life when they transgress, their soul accumulates a layer of unholy "stuff" for lack of a better word. This stuff is kind of like a callous. It renders the soul less sensitive, it is less able to appreciate the pleasure of holy pursuits. It is also less able to appreciate the pain of the transgression. The soul, itself, is less sensitive and is more likely to transgress again and again.
So the justice is happening on multiple levels. Here, while alive, a person is punished for their transgressions by not enjoying things as much as they can, and they are punished by the increased potential to increase and continue their transgressions. Then later, after death all of that "stuff" the soul accumulated needs to be removed. And that takes time and is supposed to be very painful. And all of this happens without any need for reincarnation at all. There is justice without reincarnation. At least in theory.
Now, I beleive reincarnation is possible. Though, I don't think it's required. And there's details here that I have skipped, and of course there's probably a lot I don't know about this lofty topic.