I doubt that heresies will ever stop emerging. We were warned about false prophets.
Though i do not agree with such a man as Rosmini, a fundamental issue is that of what the supreme infallible authoritative source by which Truth and error is determined and judged by is.
It has been asserted that the (one true infallible) Catholic Church is that standard, and does not need any external authority to validate it any more than God does.
But this must have a basis, and thus I have asked what the RC basis is for assurance that Rome is the one true and infallible church, to which one answer is that since the promise of Jn. 14:26* (among others i am sure) was made to the entire Church thru Apostolic succession, then therefore it is the Church Catholic (or i presume more precisely, the infallible Roman Catholic church), that is this one true and infallible church (even though the infallible part is conditional).
But this meaning of Jn. 14:26 is an interpretive assertion which itself must have a basis. It seems some RCs argue that being the historical instruments and stewards of Divine revelation and Scripture (for the RCC contends it is) means such are the infallible authorities on what it is and means (and thus on what Jn. 14:26 means), therefore dissent to it is necessarily rebellion against God (and so Prots are censured).
What is your take on the above, if you or others care to comment?
* But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you. (John 14:26)