I’m continuing to read Peter Brown’s Through the Eye of a Needle: Wealth, the Fall of Rome, and the Making of Christianity in the West, 350–550 AD and in his discussion of Symmachus he has one of those brief and enlightening explications of a word that I can’t resist sharing (pp. 101-2):
There was, however, one fissure that had begun to develop across the smooth surface of a world held together by the old-time religion of friendship: the presence of Christianity. Symmachus was what we now call a “pagan.” He has even been acclaimed by modern scholars as one of the “last pagans” of Rome. It might be more accurate to call him the “first pagan.” He was the first member of the Roman nobility whom we can see adjusting to an unprecedented situation. He was being labeled by others in confessional terms as a “pagan”; this was not a label he would have chosen for himself.
The word “pagan” itself only began to circulate widely in the 370s. It was a word used in a religious sense only by Latin Christians. (“Hellenes,” followers of the religion of the ancient Greeks, was the term used by Greek Christians.) Originally the term had nothing to do with religion. Paganus originally meant a mere civilian—a person who did not enjoy the honors and prestige attached to service of the emperor. Christians used the term to brand those who did not serve the true emperor, Christ. Such persons were outsiders; they were not fully enrolled members of the empire of God.
“Pagan” was not necessarily a hate word. It was often used in a relatively neutral manner as a convenient, idiomatic term for non-Christians. But the term did a profound injustice to Symmachus. He was not a “pagan.” He “worshiped the gods” as he had always done, and that was all there was to it. He simply did not see his fellow Romans (Christians or non-Christians) as divided between insiders and outsiders in this sectarian manner. Whatever their beliefs, he wished to treat members of his class as peers held together by the old-fashioned “religion of friendship.”
For comparison, here’s the OED (updated March 2005):
Etymology: < post-classical Latin paganus (adjective and noun) heathen, as opposed to Christian or Jewish (probably 4th cent.: see below), spec. use of classical Latin pāgānus of or belonging to a country community, civilian, also as noun, inhabitant of a country community, civilian (opposed to mīlēs soldier) < pāgus country district (< the stem of pangere to fasten, fix: see page n.2) + -ānus –an suffix. Compare earlier payen n., paynim n.
The semantic development of post-classical Latin paganus in the sense ‘non-Christian, heathen’ is unclear. The dating of this sense is controversial, but the 4th cent. seems most plausible. An earlier example has been suggested in Tertullian De Corona Militis xi, ‘Apud hunc [sc. Christum] tam miles est paganus fidelis quam paganus est miles infidelis,’ but here the word paganus may be interpreted in the sense ‘civilian’ rather than ‘heathen’.
There are three main explanations of the development:
(i) The older sense of classical Latin pāgānus is ‘of the country, rustic’ (also as noun). It has been argued that the transferred use reflects the fact that the ancient idolatry lingered on in the rural villages and hamlets after Christianity had been generally accepted in the towns and cities of the Roman Empire; compare Orosius Histories 1. Prol. ‘Ex locorum agrestium compitis et pagis pagani vocantur.’
(ii) The more common meaning of classical Latin pāgānus is ‘civilian, non-militant’ (adjective and noun). Christians called themselves mīlitēs ‘enrolled soldiers’ of Christ, members of his militant church, and applied to non-Christians the term applied by soldiers to all who were ‘not enrolled in the army’.
(iii) The sense ‘heathen’ arose from an interpretation of paganus as denoting a person who was outside a particular group or community, hence ‘not of the city’ or ‘rural’; compare Orosius Histories 1. Prol. ‘qui alieni a civitate dei..pagani vocantur.’ See C. Mohrmann Vigiliae Christianae 6 (1952) 9ff.