Atheists, tell me, a Roman Catholic: why should I become an atheist?

[Angrboda]

I mean after you have a "heretic" like Pope Honorious, or require reversals like Pope Zosimus reversing he predecessors pronouncements, how do you honestly believe that what the current pope is saying is truth and you won't be damned for following it by some future pope? [3]

3) There is a difference between material heresy (unknowingly believing something that is heretical) and formal heresy (knowingly believing something that is heretical, and publically teaching said heresy in spite of ecclesial requests to stop). There is a difference between every-day things the Pope says (non-infallible personal remarks and correspondence and interviews) and very specific things he says for the purpose of teaching (non-infallible magisterial teaching like exhortations, encyclicals, apostolic letters, etc.) and very specific things he says for the purpose of solemnly and finally defining a dogma/aspect of a dogma (infallible ex-cathedra pronouncements).

Pope Honorius may have been a material heretic. That is not a problem. Almost every Catholic is probably a material heretic in some way (i.e. there is probably something we think in good-faith that the Church teaches, but we are actually wrong about). He never, however, solemnly defined his material heresy as a dogma. If he had done that, then you would have a point.

This seems duplicitous. I'm told that Catholocism is not a religion of the book, but that the church and its traditions are the highest authority. What does it mean to say that something is true according to the highest authority on earth, yet that the teaching is fallible? It seems you are making a difference that makes no difference. Whatever the latest pronouncement of the church is becomes infallible for that time. It sounds like you want to have your cake (the church being authoritative) and eat it, too (the church only being relatively authoritative). Regardless of ex cathedra pronouncements being placed in a different "category," they have no more effect than the fallible proclamations of the church, and to claim that they are different thereby seems like nothing more than a game of words. If the church is wrong on a matter, it is wrong authoritatively, and this business about fallibility does little to alter the true impact of the church's pronouncements. Fallibly wrong with the highest authority is "practically" indistinguishable from infallible. The weight of the church resting upon any pronouncement is the same.