I think mm’s question is a valid one. Do you not have an answer?
There never is one.
Because you aren't interested in an answer, you're hoping for a blurb, without context or fullness (which sums up how Protestant doctrine comes about, btw). You don't really care about incredulity vs. apostasy vs. schism vs. heresy, either formal or material. You don't care about the balance between obedience and the need to rebuke. You don't care about the weight of Doctrine and the role of Sacred Tradition.
If I'm mistaken and you really do care, feel free to study up.
I have answer. It’s in this very article that I posted. Trying reading it before you jump into the protestant mosh pit.