1) Office of the Pope 
The ministry or work of an apostle. In Catholic usage, a term covering all kinds and areas of work and endeavor for the service of God and the Church and the good of people.
• (n.) The dignity or office of the pope, as the holder of the apostolic see. • (n.) The dignity, office, or mission, of an apostle; apostleship.
A·pos'to·late noun [ Latin apostolatus , from apostolus . See Apostle .] 1. The dignity, office, or mission, of an apostle; apostleship. « Judas had miscarried and lost his apostolate . Jer. Taylor. » 2. The dignity or office of the ...
the dignity or office of an apostle. · · the dignity and office of the pope as head of the Apostolic See. · the mission of bishops in their dioceses. · an organization of the laity devoted to the mission of the Church.