Hands down for me the best film portrayal of  a pope is Rex Harrison of Julius II in The Agony and the Ecstacy.   A sympathetic portrayal of the soldier pope, Harrison portrays him as strong, cunning, a biting wit, a true lover of the arts, and a man of deep faith who fears his service to God has been a failure.   Michelangelo was the master artist of his time, perhaps of all time, but he required a rough hewn pope to hold him to his task.

Here we see Michelangelo explaining to the Pope his conception for the ceiling.

At this link here we have the great Pope and the great Artist discussing art and faith in one of the more profound discussions to be found in a popular film.  The death bed revival of the Pope is also one of the more hilarious sequences to be found in a non-comedy!  I think both Michelangelo and the Pope would have been pleased by their portrayals in this film.  It does justice to both of them, and no subject of any work of art can ask for better.