NOTE: This is a condensed excerpt from my forthcoming (2014) commentary on Philippians.
Located on the major Roman road known as the Via Egnatia, Philippi was “a leading city of the district of Macedonia and a Roman colony” (Acts 16:12). Because of its strategic location Philippi became a strategic location for trade despite the fact it was 13 km from Neapolis, the nearest sea port.
As a Roman colony, Philippi was intended to be a miniature version of Rome. However, the Roman character of the city did not erase the previously existing Greek Hellenistc culture. As the lingua franca of the Empire, Greek was widely spoken. Many of the Greeks and Thracians in the area who were displaced by newly settled Romans remained in the area. Witherington sums it up well when he writes “We must then talk about a Roman overlay of culture and custom on top of the indigenous Greek Hellenistic culture which still continued in various ways.”
What was the population of Philippi in the middle of the first century A.D.? While any estimates must be tenuous at best, a safe estimate is 10,000–15,000. The vast majority of that population would have consisted of slaves, service providers, and peasant farmers. Most of them would have lived either at or below subsistence level. With the grant of land to retired soldiers nearly 80 years before Paul set foot in Philippi, military veterans and their families would have comprised an important minority within the population. They would have been especially influential among the elite within Philippi. Yet as a percentage of the population they would have been quite small, perhaps as low as even three percent according to one estimate. Although estimates such as these are necessarily speculative, Peter Oakes argues that about 40 percent of the population were Roman citizens, while the remaining 60 percent were “non-citizens who were largely Greek-speakers.”
Religiously, Philippi was a typical first-century city in that there were a large number of gods worshiped. One particular area that deserves mention is the possible presence of the imperial cult, in which the emperor was worshiped as a god. There is no doubt that the ideology of Caesar’s claim to be Lord and Savior who brings salvation and peace to the world would have been widely known throughout the Roman Empire and particularly in the Roman colony of Philippi. Such ideas were part of the cultural milieu, consistently reinforced by proclamations and celebrations of the emperor’s acts. But it does not follow that the imperial cult was the central religious cult in Philippi and as a result serves as an interpretive grid through which Philippians must be read; such a claim goes well beyond the evidence.
A final issue to discuss is the presence (or lack thereof) of Jews in Philippi. Since Luke refers to a “place of prayer” (Acts 16:13) rather than a synagogue, it appears that the Jewish population in Philippi was extremely small. According to Jewish tradition (Mishnah Megilah 3b, 5a), ten Jewish men were required to form a synagogue. Thus it would seem there were not enough Jews in Philippi to meet even this minimal threshold. In fact, Luke goes out of his way to emphasize that Paul and his companions spoke “to the women who had assembled” alongside the river (Acts 16:13). And Lydia, the woman singled out as the initial convert, is identified as a “worshiper of God” (sebomenē), a term that refers to a Gentile worshiper of Yahweh! Every piece of available evidence indicates a negligible Jewish presence in Philippi.
 Witherington, Philippians, 5-6.
 Oakes, From People to Letter, 44-50. He bases this estimate on the square acreage of the city, likely population density, and the size of the theatre. Other estimates range from 5,000 on the low end to 20,000 on the high end.
 Ibid., 50-53.
 Ibid., 50.