It is the Catholic Church, the only Church in continuous existence since the time of Christ.
And only the Catholic Church can settle doctrinal disputes, because it is the only Christian Church that possesses a continuous and non-contradictory body of teaching.
The only doctrine that non-Catholic Christians can agree on is... what?
As far as I can tell, that shared teaching is, "we're not Catholic."
The RCC was in existence in Christs time you say!!! How preposterous. Some of their rituals, beliefs, and vestments go back much farther than that. Way back to the Babylonians in fact.
>>because it is the only Christian Church that possesses a continuous and non-contradictory body of teaching.<<
Um, Riiiiiiggggghhhhht. Ill leave you to that dillusion.