i Register
In some senses, papalist is marked as derogatory, historical, rare. Watch for register when choosing this word.
adj
Supporting papal authority; supporting papalism or hierocracy.
The Summa de potestate ecclesiastica of Augustinus was reprinted in 1582 and again during each of the next three years, and it became a standard repository of papalist arguments. The pope, Augustinus had argued, has immediate power of jurisdiction over temporal as well as spiritual things […]
noun
A supporter of papal authority; (Middle Ages) a hierocrat.
A papist (Roman Catholic).