Although Chaldean Americans constitute the bulk of Iraqi immigrants living in the United States, they represented less than 10 percent of the population of Iraq by 2003. While the vast majority of Iraqis, like residents of other Arabic nations, are Muslim, Chaldeans are Roman Catholic, and practice one of the 18 to 20 separate rites of the Catholic Church. They also differ from other Iraqis in that their ancestral language is not Arabic but [[Chaldean Language | Chaldean language]] of Neo Aramaic. Chaldeans may also be knows as Syriac (religious term) or neo Assyrian (or Chaldean Nestorians until 1870 AD).
Chaldean Americans are a highly religious people proud of their Christian heritage. According to legend, they were converted to Christianity by the Apostle Thomas on one of his missionary journeys to the East. (St. Addai, an associate of Thomas, is revered as a Chaldean patron.) In the third century, they were followers of Nestorius, a patriarch of Constantinople who was declared a heretic by the Roman Church for teaching that Jesus Christ was not concurrently God and man. This division between the followers of Nestorius in the East and the Roman Church lasted until 1445, when some Chaldeans were received into the Roman Church by Pope Eugenius IV. They were permitted to retain their historic rituals and the Chaldean/Aramaic language for mass and other ceremonies. Searching for an appropriate name to call this new Catholic rite, the Pope focused on their the Chaldean historic native homelandof [[Mesopotamia|Mesopotamia]], the native Chaldean history and Chaldean culture, which in ancient times had been the land of the Babylonians, Assyrians, and ChaldeansBabylonians. It was also the historic homeland of the prophet Abraham, who came from Ur, a city of the Chaldeans. Hence, the Pope chose recognized "Chaldean" as the name for the new Catholic riteand as a continuation of recognition of our [[Chaldean people|Chaldean people]] as the native people of [[Mesopotamia|Mesopotamia]].
Some of the earliest members of Detroit's Chaldean American community recall hearing stories from their grandparents about the conversion of their Chaldean towns in Mesopotamia Iraq, Syria, Southern Turkey and Western Iran from Nestorianism. This occurred in about 1830, when the town recognized the Roman Pontiff as the head of the Church.