It is possible to espouse an objective error --- to hold and express an erroneous religious conviction --- without knowing it IS an error. That would be objective heresy (I think they call it "material" heresy) but it wouldn't be subjectively culpable if you were truly ignorant.
On the other hand, you are guilty of "formal" heresy only when you realize that what you believe is truly against and incompatible with a dogma of the Church, but you obstinately refuse to set your erroneous opinion aside.
I don't know if "material" heresy is enough to put you outside of the Church. I know "formal" heresy is.
It raises epistemological problems too, which just make my head go around and around. I actually am convinced that objective truth is "knowable" and that the rules of logic apply (like that elegant "Rule of Non-Contradiction") but --- is it possible that there are people whose thinking processes are so screwed up, they can't actually tell if they are contradicting themselves or not?
I might never have thought so, but I once met a maddening woman, a poet and mother of seven, whose method of thinking was so wafty-lofty and-- um, screwball--- that... oh well...
And Pope Francis' verbal style baffles me in somewhat the same way. If ambiguity is your habitual way of thinking and speaking, are you even mentally equipped to commit a clear-cut heresy?
I think the former top theology guy, Fr. Tom Weinandy, who got run off his job at the USCCB for saying in print that Francis is a problem pope who causes constant confusion, also once mused that Pope Francis may be paradoxically "untouchable" as far as formal heresy is concerned, because he seems to be incapable of constructing clear-cut declarative sentences. :o(
But that's the vexing thing. There are supposedly intelligent people out there, who keep maintaining that Francis is OK because everything he says can be interpreted in an orthodox way.
If you squint real hard and look at it sideways.
Due to that all-purpose ambiguity.
I'm torn between thinking he's either a paranoid schizophrenic, or a g@%%@$^%& Peronist.