What would it mean if someone was justified and died justified but not saved? Would they go to Limbo, or something like that?
Sortof, I think. Father Feeney, when asked, said "I don't know. Neither do you." I'll agree with that, but am speculating.
I think there's not only a "Limbo" of perfect natural happiness, where there are infants, but there's something of a continuum in this entire Limbo-like border region, with varying degrees of happiness vs. unhappiness depending on how you lived your life. Even the EENS definitions say that there are greatly different degrees of suffering.
Unbaptized Martys end up perfectly happy, and likely enjoy even a greater happiness than the infants who die without baptism.
I believe that the greatest motivation for wanting to reject EENS dogma is that some Jєωιѕн or Lutheran grandmother who lived a virtuous life, kept natural law, possibly even made a heroic sacrifice by giving her life for her children, that she ends up in the same monolithic cauldron of fire as Satanists, serial killers, blasphemers, etc.
Most people have that binary idea, where it's either unbridled joy in Heaven or eternal tortures in Hell.
This is where the distinction between natural reward / punishment /justice and the unmerited supernatural gift of the Beatific Vision, the distinction that St. Thomas first articulated eloquently comes into play, and not just for infants who die unbaptized. No, as Pius IX teaches, those who haven't committed actual sins do not receive eternal punishmetns for those.
So, just as everyone says that there are degress of happiness and glory in Heaven, and then degrees of suffering in Hell, why wouldn't there also bed degrees of natural happiness in Limbo, from perfect happiness, to more happiness than sorrow, to the opposite, etc. I think it's a sliding scale of happiness and unhappiness, and not just two monolithic places: Heaven or Hell. Either you're a saint next to the Cherubim or playing checkers with Joe Stalin and Judas Iscariot.
Then, because of this binary construct people tend to have in their brains, they reject EENS, since that Lutheran grandmother I mentioned before ... she doesn't really deserve to be cruelly tortured fo eternity just because she grew up in Lutheranism, so then they try to get her into Heaven somehow, to prevent that consequence of EENS dogma.
But if you realized that Heaven is an unmerited free gift that nobody deserves, and that our nature cannot even imagine what it's like since it's so beyond us ... then there's no punishment in not receiving the Beatific Vision.
St. Gregorn nαzιanzen, in rejecting BoD, said that there are some who are not good enough to be glorified but not bad enough to be punished. Somewhere between the punishment (of Hell) and the glory (of Heaven and the Beatific Vision, there's another Limbic type of realm, where unbaptized infants go, but quite possbily others. St. Ambrosed said that martyrs are "washed but not crowned". That's clearly a reference to having their sins washed (at least in terms of their punishment), but not entering the supernatural Kingdom, with the Crown, and the Beatific Vision.
From St. Augustine and for about 7-8 centuries it was ... there's either the glory of Heaven, Beatific Vision, etc. ... or else the fires of Hell. Eastern Fathers were a little more mysical or enigmatic about some speculative other place, such as St. Gregory's statement above. Even Our Lord said that those who believe and are baptized will be saved. But those who do not believe will be condemned. That leaves a logical middle area, where you believe (and so are not in the condemned group), but are not saved (are not baptized). So if not saved and not condemned ... where do you go?