Recently I considered the possibility of ethical (as opposed to dogmatic) universalism. Though the name is not exactly precise, I have in mind something like this. This is a universalist soteriological conviction that expresses its universalist hope in ethics rather than in dogmatic affirmation. For example, the ethical universalist prays for the salvation of all persons and expects this prayer to go answered by God, even though she does not always dogmatically affirm that all people will be saved. She may read and preach the relevant hell texts (e.g., Mt 25.46) in a way that they teach that some persons will be damned forever, though she does this for its rhetorical effect more than because she is convinced that it will actually happen. She is like Jonah, who preaches destruction and hell-fire to Nineveh but knew all along that God foresaw their repentance and would forgive the Ninevites.
It occurred to me as I was reading through Ramelli's The Christian Doctrine of Apokatastasis (Brill, 2013) that St. John Chrysostom may have been just such an ethical universalist. John studied under Diodore of Tarsus alongside Theodore of Mopsuestia, both of whom affirmed universal salvation and a limit to the punishments of the damned in Gehenna. He was familiar with the doctrine of universal salvation and was aware of the debates and arguments going on about the topic.
Let us be clear: John does argue against apokatastasis in his works and affirms the eternality of the punishments of the damned in Gehenna. Yet that's not all he does.
John is aware that the Greek term αἰώνιος does not always mean "eternal" or "everlasting," for example as when he describes the power of the devil as αἰώνιος, meaning "bound to the present aeon" and doomed to come to an end along with the end of this world (Ramelli 2013, 553). Being aware of the ambiguity of the term αἰώνιος, his argument is rather facile when he says: How, then, can that which is αἰώνιος [namely the torments in Gehenna] be temporary? (554). It is plausible that he does this because he makes use of the teaching of eternal torments in hell for the rhetorical and ethical effect it has on his audience.
On the other hand, John has some very suggestive remarks to say about the way the living can help those who've died in sin. He recommends prayers, supplications, and almsgiving, especially the prayers of the liturgy, as ways in which the living can intercede on behalf of the dead for their salvation (558). He appeals to the example of Job's sacrifices on behalf of his children, and asks: why do you doubt that we too, by acting on behalf of the dead, will be able to bring them comfort and help? For God is used to bestowing a grace upon someone even by virtue of someone else. . . . Thus, let us not get tired to help the dead and to pray for them. For the perspective [literally κεῖται, what is foreseen] is the common purification of the whole humanity (ibid.). Likewise he says that nothing is more valuable than almsgiving, and that almsgiving can put out the river of fire, suffocate the worm, destroys the chains, and extinguishes the furnaces -- all of which imagery clearly refers to hell (561).
St. John Chrysostom clearly has a moralist emphasis in all of his writing. He is particularly concerned for the treatment of the poor, and heaps up praises on almsgiving as if the simple act of charity could undo the sinfulness of a thousand generations. When it comes to speaking about the punishments in Gehenna, he declares them endless because this will motivate people to do good. But when it comes to those who've died in sin, he tells their loved ones not to worry, but instead to pray for them and to pick up almsgiving as the means by which their departed beloved can be saved.
Ramelli provides an extreme example from John's writings. Commenting in Hom. 9 on 1 Cor 3.15: He will be saved but, as it were, through fire, John says:
When Scripture says 'He will be saved,' it does not mean other than the prolongation of his punishment, as though it were saying: 'He will continue to be punished uninterruptedly.'
This is obviously a terrible misreading of the text, but for John, the moral motivation provided by threats of punishment is the ultimate end. Ramelli comments: John's paraenetic intention is here stronger than logic (556, n. 612).
Ramelli does not draw any strong conclusions, but the evidence she brings forth is suggestive. It may well be that Chrysostom, who had interactions with universalists and learned under and alongside them, may have affirmed the doctrine within his heart of hearts, even though his preaching and teaching was otherwise for some moral purpose.