That is like me telling you that I am the world's expert on a particular subject. I can claim all kinds of things, but that doesn't make it true. The Catholic Church can claim all kinds of things...doesn't make it true.
Wouldn't it be more accurate to say that we think we have MORE of the truth? We don't have the WHOLE truth, that's fer shur. And we don't think the others have NO truth. So it has NOT proclaimed itself so baldly as the repository of truth. Blitzing out nuance obscures the point, I think.
Yeah, even in my formulation there is a self-referential, self-validating quality to the claim, but let's start by getting the declaration right. Rip us up for what we DO say, not for what we don't, okay?
Which Church, do you think, St. Paul had in mind in 1 Tim 3:15?