The most common explanation I heard from Christians for the theodicy is that suffering is caused inevitably by the free will of humans. The argument is essentially that a world without suffering is impossible when you allow free will, as you can't prevent humans from causing harm to each other.
In heaven, there is supposed to be no suffering at all. How can that notion be reconciled with the free will argument? Do the humans in heaven have no free will, and are therefore unable to cause harm to each other? Or is it possible to create a world without suffering even when granting free will to the humans living in it?