Why does hell give up its dead at the great white throne judgment?
Hell gives up its dead so the unbelievers held there can be resurrected and brought before the great white throne judgment. There they are judged according to their works. After that, they are cast into the lake of fire, the second death, which is far worse than hell.
Les explains that death and hell is the place of the unbeliever who has died, waiting for the great white throne judgment. Hell delivers up the dead in it so they can be judged, every man according to his works. That resurrection out of hell is not unto life; it is only to go to something far worse, the lake of fire. The context calls this the second death: physical death and now spiritual death. Death itself is separation—physically, the spirit from the body; in the spirit realm, separation from God for eternal separation. The ones who had been occupying hell will then be cast into the lake of fire.
And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works.