The Decline of The Roman Empire - The Rise of The Roman Catholic Church!

(1) There were early corruptions in the church at Rome, as there were elsewhere, but peculiarly there, as Rome was the seat of philosophy and of power.
(2) there were great efforts made by the bishop of Rome to increase his authority, and there was a steady approximation to what he subsequently claimed - that of being Universal Bishop.
(3) there was a constant tendency to yield to him deference and respect in all matters.
(4) this was kept in check as long as Rome was the seat of the imperial power. Had that power remained there, it would have been impossible for the Roman Bishop ever to have obtained the civil and ecclesiastical eminence which he ultimately did. Rome could not have had two heads, both claiming and exercising supreme power; and there never could have been a "revelation of the man of sin."
(5) Constantine removed the seat of empire to Constantinople; and this removal or "taking away" of the only restraint on the ambitious projects of the Roman bishops, gave all the opportunity which could be desired for the growth of the papal power. In all history there cannot, probably, be found a series of events corresponding more accurately with a prophetic statement than this; and there is every evidence, therefore, that these are the events to which the Spirit of inspiration referred. -- Barne's notes on The Bible