The “thousand years” of Revelation 20 appears in the midst of a number of other dramatic and colorful figures: a bottomless pit, a great chain, a dragon/serpent, thrones, a beast, etc. Why should the pit, chain, dragon, etc., be viewed as figures, and yet the “thousand years” be singled out as literal? Such an inconsistent methodology defies common sense. The fact is, the numeral “thousand” is found more than twenty times in Revelation, and, as far as I can tell, is never employed by John in a literal sense. In Chapter 20, the most likely interpretation of the number is that of “fullness” or “completeness.”
Concerning the symbolic meaning of the number, William Milligan observes:
In the OT, the number “one thousand” is often used to indicate completion or fullness: “a thousand generations” (Deut 7:9; Ps 105:8), “a thousand hills” (Ps 50:10), “a thousand days” (Ps 84: 10), “a thousand shields” (Song 4:4). Whatever the actual number is, a “thousand” is used to represent the entirety of it. So when God says he owns the cattle on a “thousand hills,” the “thousand” refers to the actual number, whatever it may be (10, 100, 1000, 1,000,000, etc.), while also saying that God owns the complete or full number of cattle. When God says he will keep his covenant to a “thousand generations,” it doesn’t mean a literal “thousand” generations. It means that, whatever the number of generations is (again, 10, 100, 1000, 1,000,000, etc.), God will keep his covenant completely or fully. Thus, the basic idea that is communicated by the number “one thousand” when employed figuratively is that of “completion” or “entirety.”
So when we read of the dragon being bound “a thousand years,” we should understand the figure in like manner. By saying the “dragon” (which I understand to symbolize sinful desire manifesting itself as a persecuting power against God’s people) was bound a “thousand years” John means that this persecuting power was completely and fully bound - i.e., the dragon’s power to deceive the nations into violently persecuting the Church was taken away entirely for a period of time (we know this binding was only temporary because the dragon is later represented as being released from its prison). The beginning of the dragon’s binding likely corresponds to the ascent of Claudius to the imperial throne (who may be the enigmatic “restrainer” referred to by Paul in 2 Thess 2:6-7). The binding of the dragon ended after Nero (whose mother, Agrippina, had Claudius poisoned) ascended the throne and began to wage war against the saints in AD 64. This period of violent persecution lasted almost exactly 42 months, or 3 1/2 years (see Dan 7:25; cf. Rev 13:5).
And in saying that the beheaded martyrs “lived and reigned with Christ a thousand years” (which I understand to be figurative imagery expressive of vindication), John means they were completely and fully avenged and vindicated by God. The vindication and avengement of the beheaded martyrs likely took place when Nero, after having been declared a public enemy by the Roman Senate, committed suicide in June of AD 68. Nero’s death was followed by the execution of many of his allies. When John adds that the “rest of the dead did not come to life until the thousand years were ended,” his meaning may be that the rest of the righteous dead would not be avenged and vindicated until sometime after the death of Nero. This, I believe, took place at the fall of Babylon, the “great prostitute” (i.e., 1st century Jerusalem). At this time in history, “all the righteous blood shed on earth, from the blood of innocent Abel to the blood of Zechariah the son of Barachiah” came upon that 1st century generation of unbelieving Jews (Matt 23:29-36). That the rest of the righteous dead were avenged and vindicated by God at this time in history is evident from the following verses: