In addition to the Catholic Church (Roman and Uniate) there are also the Eastern Orthodox Churches, the Non-Chalcaedonian Churches (Miaphysites or "Oriental Orthodox"), and the Non-Ephesenes or Nestorians.
As far as I am aware, each of these view the others as having valid sacraments and view the moral teachings (how to live) as legitimate. It is the beliefs about God and the Church that are in dispute. NRx, please correct me if I am wrong.
Now keep in mind that each and every one of the above has a legitimate claim to going "all the way back." How in the name of all that is reasonable does one sift through all this and find "the real thing" when the only means to do so is to accept the internal criteria of the church decided upon?
I think the first step in answering this question is to determine what is the authentic branch of Judaism and from there to work forward into Christianity.
One side seeks an Absolutely Authentic Bible, the other an Absolutely Authentic Oral Tradition. Close but no cigar. One side seeks an authentic Bible, the other side seeks an authentic Bible and authentic Oral Tradition.
Yet everyone agrees absolutely that at one time Judaism was the One True Religion, that its Bible was undoubtedly true and that its Oral Tradition from Sinai was undoubtedly true. The problem is that people insist its place was taken by something else--and people have been fighting for two millenia about just what that "something else" is!
While I agree the Oral Torah was given to Moses at Mt. Sinai and was preserved, most Christians either do not know or disagree. However, at the time of J*sus, the Jews were split into Hellenists, Zealots, Essenes, Sadduccess, and Pharisees (possibly more). This does not include the Samaritans which in turn claimed Sola Scriptura and stated that the other groups were not the true Jews. Since then, Karaites, Reform, and Conservative Jews have been added as well as [not]Jews for Jesus and a myriad of other insignificant denominations.
All legitimate longings are answered in Judaism--the desire for an unquestionable Book, an unquestionable Tradition and an unquestionable Authority as well as the simultaneous but apparently contradictory desires for universal and particular Truth, for the destruction of ancient myths and the validation of Ancient, Unchanging Truth.
Unfortunately, the Jewish equivalent of
Apostolic Succession died out and modern rabbis are not true rabbis.
“As far as I am aware, each of these view the others as having valid sacraments and view the moral teachings (how to live) as legitimate. It is the beliefs about God and the Church that are in dispute. NRx, please correct me if I am wrong. “
There is not a uniform understanding of the sacraments. Rome has a differing understanding of grace and the nature of the Church which is very problematic from our POV. The Orthodox Church doesn’t really do the whole “valid” sacraments thing. We refer to sacraments as being with or without grace. And the historic teaching of the Church has been that there are no sacraments outside the Church. Rome has always accepted this, but then turned around and made the teaching meaningless by proposing an invisible church that has no boundaries. Thus from their perspective anyone, including even non-Christians can baptize someone if they use the correct form and matter. This is nonsense from the Orthodox perspective.