Telstar, the rejection of infernalism (which is what von Balthasar labeled those who believe in an everlasting punishment/torment for humans) is predicated on two things. 1. God’s love and mercy are infinite in nature and extent. 2. The sacrifice of Christ took him to the outer limits of godforsakeness (which would include hell). That’s it in a nutshell. When those two truths are pondered deeply, a hope that hell will one day be emptied of human souls follows rather smoothly.
I’ve brought up other arguments here (the disproportionality/injustice argument, the rejection of libertarian freewill, an argument against Aquinas’ psychological “no exit” argument, etc). But, what von Balthasar did was to consider as deeply as he was able the two truths I list above and the implications of those truths for human salvation.
We all love and obey the Church as best as we are able. No one is looking for loopholes. No one is trying to rebel and deny dogma. Rather, we are looking for a position that takes into account all of the data.
To reiterate, this von Balthasar position of hope is not apokatastasis (there are reasons for believing that fallen angels cannot change their minds)
It is not a rejection of a belief in hell.
It is not a rejection of a belief in the punitive nature of hell.
It does admit that there could be human occupants in hell.
It rejects the infernalist position (everlasting punishment/torment/suffering for the human)
It rejects libertarian views of free will because the greatest minds of the Church have also rejected that position (e.g., Sts Augustine, Aquinas, etc).
It is a position more compatible with our common sense of justice (a punishment is proportionate to the crime).
It accepts that Christ died for all.
It accepts that God is love.
It accepts that God desires all to be saved.