The other was almost as good. Yet one goes to a permanent reward in heaven and the other is eternally tortured in Hell without any hope of mercy or relief. The latter is being punished severely, for all time, because of one little sin too many, or one minor good deed too few. If that sinful act had not been committed, or if they had done one additional good deed, the person would have gone to heaven. They feel that a loving God is incapable of creating a place of eternal punishment.
None allow torture.
None allow unending punishment. Our attempts at fundamental justice are limited. Since God is all knowing, and loving and forgiving, it is inconceivable to many that God would create a Hell. Hell is described as being under the earth. However, in spite of numerous deep drilling projects, it has never been located.