Catholic integralism is the true seamless garment.
A thumbnail of the full Christian faith, the Catholic faith: God, Christ, Trinity, hypostatic union (Christ, true God and true man), Mother of God, communion of saints, intermediate state for some of the dead, infallible church, bishops, Mass, sacraments that do what they signify, baptismal regeneration, auricular confession, and the right, not a requirement, to use images in worship (all can, some should, none must).
The flashpoint of all orthodoxy vs. all sin is where God and his creation in the flesh meet: the fallen angels vs. humanity, who Jesus is, the Eucharist, and sex. Iconoclasm falls under this. (It's related to who Jesus is. You don't have to use images but can't condemn them.)
With only the Vincentian canon or the first seven church councils you pretty much get Catholicism. How about that?
Liberals admit that early on you end up with it, but say it was a human process, not an infallible church.
Every ancient church, even the heretics, thought only they were the true Catholics.
Today, according to Catholicism, you have what I call the great Catholic family of valid orders, of real bishops and real Masses, our corrected branch theory. Valid orders: basic credal orthodoxy (the Nestorians pass!), unbroken apostolic succession, and unbroken true teaching about the Eucharist (sorry, Anglicans; Reformed doesn't pass - we take your framers at their word).
That leaves you with these contenders: Rome, the biggest communion, Catholic splinters such as the Old Catholics and their American offshoot, the Polish National Catholics, and all the separated Eastern churches (not "the Eastern Church": there's more than one and they long didn't recognize each other): the Orthodox (the second biggest communion), the Monophysites/Miaphysites, and the Assyrians/Nestorians.
Let's clarify the thumbnail by adding some negatives: no adulterous second marriages (without annulments) and no contraception. Related to sex, part of the flashpoint of all rebellion against God.
Who's been faithful to this?
Who's not limited to one rite or set of cultures?
Who has fulfilled Jesus' Great Commission to teach all nations?
"On this rock I will build my church." Not the man (he can be a private heretic or unbeliever); the Pope's office as part of the episcopate and part of the church's infallibility, explaining our teachings.
