These "Nestorian" Uniates received the name "Chaldeans" from the Roman Curia, which had given the ancient name Chaldaei to them. Successive bishops and their followers from the Church in the East returned into communion with Rome in the 17th, 18th and 19th centuries, forming the Chaldean Catholic Church. The Chaldean Catholic church and the Roman Catholic church are two branches of the one Catholic Church. At Mosul there is a patriarchal seminary, distinct from the Syro-Chaldean seminary directed by the Dominicans. This church was recognized by the Roman Catholic church and was later called Chaldean. There are about fifty-two Chaldean schools (not counting those conducted by Latin nuns and missionaries). In the 5th century, the Church of the East embraced Nestorianism, a A Chaldean Catholic priest from Iraq living in the US discusses his Church’s ancient liturgical tradition as well as the dangers faced by Middle East Christians today. In fact, they have much more similarities than differences.

The Chaldean community originates from groups of adherents of the Church of the East that entered into communion with the Roman Catholic Church in the 16th and 17th centuries. Chaldean Catholic Church, Eastern rite church prevalent in Iraq, Iran, and Lebanon, united with the Roman Catholic Church since 1830, and intermittently from 1551. Christianity in Iraq and Iran dates from the late 2nd century. Chaldean Church rejection of its Assyrian heritage and its leaders' insistence that they are ethnically Chaldeans is contrary to all historical facts, reason and logic. The Chaldean Church and the Roman Catholic Church have many similarities. The Roman Church is found globally while the Chaldean church mainly only exists in Iraq and neighbouring countries. In 1830, Rome established the Patriarchate of Babylon of the Chaldeans, which strengthened and unified the Church. The name Chaldean had became fashionable among the Christians since the 12th century AD when some syriac writers such as Basil Bar Shumana came to believe that the city of Urfa known as Urhay in northern Mesopotamia was the ancient sumerian city called Ur of Chaldee of the Old Testament from which … The community emerged after the schism of 1552. Other bishops and believers from the Church of the East have joined as recently as 2008. The Catholic Chaldean clergy number 248 priests; they are assisted by the religious of the Congregation of St. Hormizd (Rabban-Hormizd) who number about one hundred.