The core failure IMNSHO is your assumption that promises made concerning the 'church' apply to the institutional church. The reality is that for a significant period the leadership was 100% corrupt; the papacy for well over a century occupied by men in whom the grace of Jesus was wholly invisible; the existence of 2 or even 3 popes, as well as the exclusion of the Bishop of Rome from his own diocese for many decades points to total apostasy by any reasonable standard. Remarkably it did recover - but claiming apostolic succession through that chaos is fantasy.

And in any argument over legitimacy, Eastern Orthodoxy, with 4 patriarchs to Rome's one including the see of which Peter was first bishop before Rome, has as good a claim to it as Rome has.

Given that confusion and the reality that God is willing to work through many different denominations, the case for treating Rome as special is invalid to my mind; there is no justification for choosing to be an RC over any other denomination.

A particular argument against Rome is to be found in the formularies surrounding the doctrine of the Assumption. In that the document it states:

"45. Hence if anyone, which God forbid, should dare willfully to deny or to call into doubt that which we have defined, let him know that he has fallen away completely from the divine and Catholic Faith."

http://w2.vatican.va/content/pius-xii/en/apost_constitutions/documents/hf_p-xii_apc_19501101_munificentissimus-deus.html

This implies that all the rest of us have fallen away completely from the faith. That's not acceptable unless the sentence is to be evacuated of meaning anything. Yet the Pope goes on to state:

"47. It is forbidden to any man to change this, our declaration, pronouncement, and definition or, by rash attempt, to oppose and counter it. If any man should presume to make such an attempt, let him know that he will incur the wrath of Almighty God and of the Blessed Apostles Peter and Paul."

So the colours have been nailed to the mast - yet modern catholics come up with the sorts of comments you try to make about other 'ecclesial communities' being in the faith. Whilst attractive, it's not actually consistent with the dogmatic teaching of that infallible document. The existence of that document is thus a wound in the body of Christ for which the Papacy should repent; that it acts in ways that reveals that it doesn't actually mean it only makes it guilty of hypocrisy as well.

Turning to other matters. You fail to recognise the significance of the collapse of Brazil particularly as a Catholic country. Once, not long ago, it was an overwhelming Catholic country. It now sees far more people in Protestant churches on a Sunday than in Catholic ones. This, to me, is a sign that the religion of the people was an outward form, with no spiritual reality. It's not a number count - as you do point out, numbers are not everything. It's that this collapse is a symptom of a dead institution.

You don't really engage with the history of the Reformation, the failed Crusade against Elizabeth and the impact of the weather on history. Whilst not conclusive, to me it is highly significant... The point to bear in mind about the Elizabeth persecutions - which killed less people over a far longer period (45 years) than Bloody Mary achieved in her FIVE years - was that the victims were mostly priests - i.e. professional agitators committed to the overthrow of the lawful government. And in 1605 the Catholic Terrorist Guy Fawkes tried to blow up the houses of Parliament... In that context treating the agents of Rome as dangerous criminals seems justified. Whereas Mary executed anyone who wouldn't sign up to be a good Catholic.

The persistence of the use of Latin in the public worship of the church is perverse; Christianity is a faith in an incarnated God - so He is to be worshipped in the culture of today, not that of a particular past. It is dangerous theology to argue otherwise. Which isn't to defend ALL that passes for Christian worship...

Overall? You want to be a Catholic? You're part of a denomination that includes much that is unacceptable, though clearly God has worked through it, as with most other denominations. But to argue for it as the only proper home for Christians? No chance...