The Imperial Church

In Niven and Pournelle's Second Empire of Man, as in Poul Anderson's Terran Empire, English has become "Anglic." However, I think that, in another volume of the CoDominium future history, the word used is "Angelic," which is neat because the Empire of Man is officially Christian.

Three religions are mentioned:

Islam on the planet, Levant;
the Church of Him, founded on New Scotland in 2882;
the Imperial Church.

Again, in Anderson's Technic History, the Jerusalem Catholic Church is either a new denomination founded in the future or the Roman Catholic Church with its headquarters moved back to Jerusalem. It is probably the latter. For example, it has religious orders, e.g., the Galilean Order.

Unless the meaning of the word "Cardinal" has changed, the Church in the Empire of Man is Roman Catholic. A Cardinal blesses a spaceship and the Cardinals are the electoral college for the Papacy. I deduce that the Pope resides not on the devastated Earth but on the planet Sparta, of which he might be the Bishop or Archbishop.