Who is The Papal Nuncio from The Autumn of the Patriarch and what is their importance?

The Papal Nuncio, who is the head of the Pope's mission in the nation, is asked to declare the General's deceased mother, Bendicion Alvarado, a saint. He refuses to do so, declaring the miraculous picture on her bed sheet is actually just a cheap paint job. Nuncio is run out of the nation and sent adrift on a raft in major sea lines.