But if an Ecuмenical Council can teach serious error, all the Popes and bishops and theologians can teach serious error for >60 years, etc. ... how is it that you cite the St. Alphonsus as an "authority"? If these previous could be wrong, then why couldn't St. Alphonsus be wrong, and his is just another opinion?
This kind of selective filtering of authorities is common with the pro-BoDers.
1) they'll assert that the Church Fathers unanimously believed in BoD (as a number of Trad BoD apologists have claimed) ... whereas at least 5-6 Church Fathers explicitly rejected it, compared to the 2 that allegedly held it (St. Augustine as a tentative opinion later retracted, and St. Ambrose arguably at best). For some reason, the anti-BoD Fathers are ignored or "filtered out", whereas Augustine and Ambrose are cited as ultimate authorities. What were these other Fathers, chopped liver? At least Karl Rahner had the honesty to admit that the Fathers generally had no use for a BoD, and to the extent they did limited it to formal catechumens. Patristic scholar Jurgens stated that not only is there no evidence that any notion of exceptions to Baptism existed among the Fathers, but, rather, the opposite, so much so that it might be considered revealed that there's no salvation without the actual Sacrament of Baptism.
2) BoDers will beat Feeneyites over the head with citations from St. Thomas, but often at the same time suddenly forget his "authority" when he taught that there can be no salvation without explicit faith in the Holy Trinity and Incarnation.
These examples of dishonest authority filtering demonstrate confirmation bias, that something other than objectivity drives the belief in R&R.
So, similarly, you'll claim that we have to accept the pre-Vatican II theologians on BoD, but then it's OK to reject the post-Vatican II theologians who unanimously teach that Vatican II and the NOM are Catholic. What happened to the OUM in the early 1960s?