Ok, but I thought we were talking about +ABL and hindus? There are 3 different salvation questions and if they are mixed together, confusion reigns.
1. Non-catholics / BOD-BOB
2. Baptized heretics / rejection of error
3. Catholics in material heresy
Just like not every catholic who was infected with the Arian heresy was damned, so not every Donatist was. Only God knows the extent to which they accepted error. In the beginning years, Anglicans in England were basically 99% catholic except they rejected the pope (not that this rejection is a small matter, but it's an example to show that heresy can often be only 1 error, while all the other beliefs are true.) Did every Englishman who went along with Henry VIII fully understand the error? Maybe not. Only God knows.
OK yes, you're right. That's confusing.
I'm honestly skeptical that the invincible ignorance principle, even if its true, can be extended all the way out to Hindus and other polytheists. The best argument I could think of for it is an explicitly scriptural one, Acts 17:30, but even then there are a couple problems with that. One of them being, I'd be arguing for my own interpretation, which is questionable, and would need to be confirmed in some way. Second: the Greeks still acknowledged "the Unknown God" ie. they acknowledged that they did not fully understand, that they were still missing something. Third: God could overlook their ignorance, but that still might mean they end up in Limbo (barring other mortal sins that they're damned for.)
Even St Justin's argument, the way I'm understanding it and arguing for it, could plausibly exclude all polytheists whatsoever on principle, and frankly, I think that's probable, even if he's right (which is uncertain.)
So I guess in different places I've been arguing for #1 and for #2. I've been arguing for the possibility of #1 based on St Justin, and for the possibility of #2 based on St Augustine. I believe Feeneyites would reject both.
#3 wasn't what I had in mind or what I was discussing, everywhere, since I think everyone (at least here... the Dimonds do push this one sometimes) think that someone in category #3 can be saved.