Pope and Apostle should be just under saint.
Why? Sure, the Pope isn't a Saint - if only for the reason that to be Pope, one has to be alive, and to be a Saint, one has to be dead (at least, in the Catholic church). Other churches call anyone who is currently in heaven a Saint. Yet other churches consider anyone having the same faith as their to be a "Saint". ("The Church of Jesus Christ of Latter-day Saints" is an obvious example of such a church). And you probably don't want to be considered a Saint in the eyes of a Discordian.
But the Pope is the infallable representative of Christ on earth. Which would rank him directly below Christ. And one can be canonized (the act that makes one a "Saint") without ever holding any rank in a church or religious organisation. So, one might argue a Pope "ranks" higher than a Saint. Or draw the conclusion they cannot be ranked together.
As for Apostles, in the Catholic church, Bishops are seen as the successors to the Apostles. So, you'd might rank them close together.
Personally, I don't care. Order them in alpabetical order, and I won't complain. Now, if they had ranked Dumbledore above Gandalf, then I'd be upset.