Then please help me understand how that is NOT the truth. When a Pope makes ex-cathedra proclamations and pronounces anathemas against those who do not accept these dogmas, how is that different than what I said? How have I misunderstood?
Now if a CATHOLIC were to disagree with the definitions, that's a big problem. at the very least he needs to quit being a Catholic if he's going to hold and teach an opinion at variance with which is defined.
But you are aware of no obligation of obedience to the Magisterium. So, painting it in the worst and most confrontative way (forgive me, I'm doing it to clarify the thought, not to be snarky) your ignorance is technically "invincible." So it is not culpable. A Catholic who put himself forth as a teacher, at the BEST construction, would be culpably (vincibly) ignorant because he ought to know that he should study the Church's teaching.
In any event, MY OWN PERSONAL view is, unlike yours, that if we could learn to get along in one 'visible' Church we would all have the riches which fervent and learned (and aesthetically graced) Protestants and other non-Catholics have, while you all would share what I, at least, think are the wonders of the Catholic Church. SO, we acknowledge and accept that their are non-Catholics who have a lively and saving relationship with Christ, while they disagree with us on matters we hold to be of critical importance. And also SO if you do not want to accept our Marian Dogmata, you really shouldn't join the Catholic Church. (That may seem obvious, but there seem to be a great many Catholics who don't get it, most of them in politics, evidently.) AND we think that by not agreeing and by staying out you miss out on lots of good stuff.
BUT that doesn't mean we think your passport will necessarily rejected at the Pearly Gates Immigration Department.