David Bentley Hart has set off some theological fireworks with his book That All Shall Be Saved. In it he argues that any teaching that does not proclaim the final salvation of all is incoherent and indeed monstrous.
The eternity of punishment in hell is the point of controversy. But it seems that both sides in the controversy overlook an important point: time is only a creature, and like all creatures will be transformed in the New Creation. Therefore, it makes no sense to think of punishment going on forever in the type of linear time in which we live.
Time, as we know it, involves coming into being and passing away, that is, death. Beings in linear time are always passing away. As Augustine pointed out, the past no longer exists and the future does not yet exist. All that exists is the moment, which instantaneously becomes the past and ceases to exist.
But in the New Creation God will transform this into the pleroma, the fullness, when God will be all in all. Time in the New Creation will not be the linear time we know, and will not involve a coming into being and passing away. We cannot comprehend this, but we know it must be true, because death will be no more.
Those who have raised objections to the arguments of von Balthasar and Hart often forget this transformation of time. Some of them also indicate that they will be disappointed if all will be saved, after all the solemn warnings Scripture and the Church have given. Jonah is their patron prophet. Jonah knew that God would not carry out his threats, that God was a softie, and that He would make Jonah look like a fool. Better that Nineveh should be destroyed with all its infants and animals, than that Jonah should be embarrassed. Better that all the unbaptized should burn in hell forever, including the majority of the human race which dies probably before birth, and definitely before the age of reason, than that the necessity of baptism should be called into question.