Is the belief cruel? You might say that God is cruel. But is the person who believes this of God also cruel? Why? If God does not exist, no one has or will be punished, and so no one is hurt. If God exists, but does not intend to punish souls in this way, the same applies. Cruelty can only exist when there is an object of cruelty.
But if God exists and does intend punish souls in this way, then that is the fact of the matter. There is nothing that the believer can do to prevent the suffering.
David Hume had the interesting theory that all professed believers are really atheists. He says that all Catholics condemn the St Bartholomew's massacre as cruel and inhumane. Yet these are the same people, he says, who condemn non-Catholics to eternal torment 'without scruple'.
Currently being discussed at the Quodlibet forum.