I was told there are similarities in the function of the pope in the New Testament and the high priest in the Old Testament. How so?
The function of the pope in the New Testament is similar to, though not identical with, the function of the high priest in the Old Testament. For example, the high priest offered the greatest sacrifices to God (e.g., on Yom Kippur, the Day of Atonement) and functioned as the earthly leader of God’s people.
While Christ is our high priest with respect to sacrifices (he offered the great sacrifice of himself; see Hebrews 7-10) and is the ultimate head of all God’s people, he has left Peter here to serve as his visible representative in his absence. The pope, as the successor of Peter, thus has a function similar to that of the high priest as the earthly head of God’s people.