Is the pope addressed as "Vicar of the Son of God" in the Donation of Constantine?
How can you claim "Vicar of the Son of God" isn't the official title of the pope? This is how the papacy is addressed in the Donation of Constantine--proof enough the Pope is the beast of Revelation 13.
The spurious Donation of Constantine does use the expression "Vicar of the Son of God," but only in passing, not as "the official title of the Pope," and it applies the title to Peter alone, not to his successors--that is, it's not used as a title for the popes in general and so is no title for them at all.
"Vicar of the Son of God" is employed by anti-Catholic writers in place of authentic titles such as "Vicar of Christ" or "Servant of the Servants of God" because it tallies up to 666--the number of the beast--and the others don't.