(1) Tertullian opposed the study of pagan literature on the part of Christians because he believes that after Jesus Christ Christians don't have a need to speculate or research any further than the gospel. There isn't a desire to believe anything else so why look at other things.
(2) Clement of Alexandria favored the study of pagan learning because before the Lord philosophy is what helped the Greeks gain righteousness and it supplies a preparatory teaching for those who will later embrace faith. Saint Augustine approved of pagan learning because knowing everything from geometry, music, grammar, and philosophy is useful to guard your faith from attacks. It's a way to defend yourself because you can explain both sides and not just the facts from the side of Christianity. It helps emphasize your faith.
(1) Gelasius thought priests had a greater responsibility than secular rulers because priests would answer for the kings lives at the day of judgement. Priests would decide if rulers deserved salvation or not.
(2) The pope the argument that emperors had no business dealing in divine affairs because meddling in divine affairs would obstruct their decrees in mundane manners and what would happen of they were in charge of making laws and silent manners concerning the service of God? There is much danger in having the power to punish people spiritually and by the law.
(3) Gelasius proposed that the emperor should solely deal with the affairs of laws and not with divine affairs. Priests and bishops should deal with divine affairs because the divine judgement cannot be overthrown by anyone's power and should be handled by people that are not in power.