How do you interpret Revelations 2:13 "Pergamum...the place where Satan dwells"? Some interpret this to mean that Satan needs a physical headquarter on earth to operate. He did then, and he still does today. "Where" on earth today, is another question. But is this true?
Pliny the Younger's letter to Emperor Trajan in the early second century shows persecution of Christians in Asia, while not systematic, was on the increase. Pliny describes how he would not seek out Christians, but if sources would identify Christians by name, Pliny would confront them, compel them to deny Jesus, and render offerings to the state gods. Refusal to do this would lead to the Christian's execution.
Revelation 2:13 is almost certainly alluding to Pergamon's importance for Rome's emperor cult, which enforced worship of the state gods and even the emperor himself, and is likely the circumstance that led to the death of Antipas in that city. The 'throne' itself may be referring to a pagan temple or altar in the city, though not everyone thinks so.
Laszlo Gallusz, The Throne Motif in the Book of Revelation, 203:
The reference to Satan's throne is tied specifically to Pergamon, which, according to Pliny, was considered 'by far the most famous place in Asia'. Ramsay argues that the reference to a throne in connection with the city implies dignity and eminence, since 'no city of the whole of Asia Minor...possesses the same imposing and dominating aspect'.
James Kelhoffer, Persecution, Persuasion and Power, 157 (italics original):
The references to "the throne of Satan" and to Pergamon as "where Satan lives" likely implicate oppression from the imperial cult as the cause for Antipas' death.
Craig Koester, Revelation, 286.
Revelation locates Satan's throne at Pergamum because it is the only one of the seven cities where a Christian has been put to death (2:13). Although Ephesus, Smyrna, Sardis, and Laodicea were also judicial centers (Pliny the Elders, Nat. 5.105-26; Magie, Roman, 2:1059-63), Pergamum is the only city where a Christian has been executed (Aune; Friesen, "Satan's," 366).
Koester rejects connecting the 'throne' to cultic sites around the city.
The Oxford Dictionary of the Christian Church (ed. Frank Cross, Elizabeth Livingstone), 1264:
Here it is referred to as the place 'where Satan's throne is' and 'where Satan dwelleth' (2: 13). As Pergamum was the first city in Asia to receive permission to worship the living ruler, the allusion here is presumably to Emperor-worship. This permission had been granted by Octavian (Augustus) in 29 BC, although the temple was not erected until 19 BC.
Gregory Beale, The Book of Revelation, 246:
"The throne of Satan" in Pergamum is a way of referring to that city as a center of Roman government and pagan religion in the Asia Minor region. It was the first city in Asia Minor to build a temple to a Roman ruler (Augustus) and the capital of the whole area for the cult of the emperor. The city proudly referred to itself as the "temple warden" (neokoros) of a temple dedicated to Caesar worship. Life in such a politico-religious center put all the more presurre on the church to pay public homage to Caesar as a deity, refusal of which meant high treason to the state.
Furthermore, Pergamum was also a center of pagan cults of various deities. For example, the cult of Asclepius, the serpent god of healing, was prominent in Pergamum; the serpent symbol of Asclepius also became one of the emblems of the city and may have facilitated John's reference to "the throne of Satan" (cf. 12:9; 20:2)! Zeus, Athene, Demeter, and Dionysus were also gods receiving significant cultic attention.