Short answers, pulled from the story.
Early Christians used the Latin term paganus to label those who did not follow their faith. The word originally meant civilian or non-combatant within Roman military jargon before evolving to mean country dweller or rustic person by the mid-fourth century.
Christian writers like Tertullian and Augustine contrasted civilians with soldiers of Christ to create a spiritual distinction between pagans and faithful citizens. They focused on whether someone worshipped the one true God rather than distinguishing groups by the number of deities venerated.
Proclus lived from 412 to 485 and Damascius from 458 to 538 as heads of the Athenian School while Simplicius of Cilicia moved to Persia after the school closed. These scholars transmitted Greek philosophy into Islamic worlds through commentaries on Aristotle and strategic refutation of doctrines.
The city of Harran successfully adopted the protected legal status of Sabians mentioned in the Quran following the decree issued in 830. Thābit ibn Qurra lived from 836 to 901 and founded the most influential scholarly line within this community.
The word pagan was not attested in English until the 17th century when Edward Gibbon used it in his Decline and Fall of the Roman Empire published in 1776. Early Christian writers initially used alternative terms like hellene gentile and heathen to describe these groups.