The Hebrew Catholics actually have permission from Rome to incorporate certain elements of their Jewish spiritual heritage into their Catholic practices and identity (almost a “rite” if you will).
They are comprised not only of Jewish converts to Catholicism, but also those who have discovered their Jewish ancestry and the like. They will also use Hebrew in their prayers, such as when making the Sign of the Cross: “B’shem ha’Av, vhaBen, vRuach Hakodesh, Elohim Echod, Amen!”
As has already been well stated, there are many Jewish elements, as could be expected, in the traditions and rites of Christianity.
The Ethiopian Orthodox Church (which has a Catholic branch as well) is perhaps the most “Jewish” of the Churches. Ethiopian Christians are circumcized at their baptism, they honour both Saturday and Sunday as the one Sabbath, they honour Old Testament Saints very highly (the feast of Abraham, Isaac and Jacob is a national day in Ethiopia) and they remove their shoes in church (as do other Oriental Orthodox). They also wear fringed prayer shawls in Church (I have such a one, decorated also with crosses at the fringes).
Most interestingly, they construct and highly honour a copy of the Ark of the Covenant in their Churches (such arks are always named after a saint). Their priests and bishops hold hand Crosses and at the end of the handles there is always a square with ten dots or symbols on it to signify that it represents the Ark of the Covenant - they honour both the Cross and the Ark as bearing the “Shekinah” or Presence of God. They venerate our Lady, the Mother of Zion, very highly and see her as the Ark of the New Covenant. They also honour “Seven Covenants” six from the Old Testament and then the New Testament.
Last weekend, I visited a local Ethiopian Orthodox parish here in Toronto where I was met with the parish priest. He stood arrayed in a purple robe and held a large and very beautiful bronze Cross which he held out to me to kiss and he then pressed it to my forehead. He also asked me to remove my shoes. I noticed they also have musical instruments and perform liturgical dance before their Arks, as did David of old.
The Assyrian Church of the East likewise has many Judaic elements and I believe they do refer to their priests as “Rabbi” - I don’t know if the Catholic Chaldeans do the same.
Also, in Florence, the magnificent Church of Santa Croce has a large Star of David over the main entrance - this was purposely constructed by the church’s architect and builder who was a Jewish convert to Catholicism.
In the Russian Orthodox Church, there is a much venerated priest, Father Alexander Men, who was a Jewish convert to Orthodox Christianity. He adopted numerous Judaic practices, including the use of a Menorah in his private Icon shrine. He helped many Jews into the Church. He was found dead at a train station, having been killed with an axe, as he waited to be taken to Moscow to celebrate the Divine Liturgy.
A Russian New Martyr under the bolsheviks, St Alexander Jacobson, was a doctor who worked among victims of the communist terror. A Jewish convert, he placed little icons of the Mother of God at the bedside of his patients and frequently made the Sign of the Cross. Several of his bewildered patients would notice this and would ask him whether he was Jewish or Orthodox. . . He would often reply, “I am an Orthodox Jew . . .”
As he refused to curtail his outward expressions of his Christian piety, and insisted on keeping icons of our Lady out in rooms when he performed operations, he died a martyr for Christ.
Shalom Aleichem!
Alex