The map that petike submitted groups several denominations together, so I wouldn't know if Catholicism is a plurality the way they define the groups.
Anyway, some names
Cecilia
Calvertia
Cavertland
Baltimore
Georgia (after the King, or after Cecil Calvert's father)
Annland (for a more Protestant friendly renaming around the time that Ann Arundel Town was renamed to Annapolis)
Cecilia would probably work. Maybe Calvertsylvania. Or Queensland?