Millennialism (also called millenarianism) describes the range of Christian views on the thousand-year reign of Christ described in Revelation 20. Three primary positions exist:
Premillennialism: Christ returns before the millennium to establish a literal 1,000-year reign on earth, followed by the final judgment. Historic premillennialism (Papias, Irenaeus, many early fathers) and dispensational premillennialism (Darby, Scofield) are its main forms.
Postmillennialism: Christ returns after the millennium — the gospel progressively transforms the world, ushering in a golden age before Christ's return. Optimistic; associated with Puritan and Reformed strands.
Amillennialism: The "thousand years" is symbolic for the present church age — Christ reigns now through His church; there is no literal future earthly millennium. Augustine, Calvin, and most Reformed and Lutheran traditions hold this view.
Millennium (n., Webster 1828): A thousand years; the period of a thousand years, during which, according to an opinion, Christ will reign on earth before the final judgment. "The millennium is a period expected by many Christians in which righteousness and religion will prevail greatly, or universally." The three-way distinction (pre/post/amillennial) developed fully in the 19th–20th centuries, though the underlying debate is ancient.
Date-setting is millennialism's perpetual corruption — from William Miller (1844) to Harold Camping (1988, 1994, 2011), each predicted rapture has left theological wreckage and public mockery. Dispensational charts have sometimes replaced the gospel with an eschatological calendar, making prophecy speculation the main business of the church. Conversely, over-realized eschatology (the kingdom is only spiritual, only present) can produce a church indifferent to Christ's physical return and final judgment. The antidote: "No one knows the day or the hour" (Matt 24:36) and "Occupy till I come" (Luke 19:13 KJV).
Latin: mille (thousand) + annum (year) → millennium (~1638) → millennialism (theological usage ~19th c.) Greek text of Revelation 20:2,3,4,5,6,7: χίλια ἔτη (chilia etē) — a thousand years (6 occurrences — the repetition signals significance) Three positions named: pre-millennial (~1800s formal coinage) post-millennial (~1700s, associated with Whitby) a-millennial (~1930s, coinage by Jay Adams and others)
chilia (χίλια, G5507) — a thousand; root of chilialism (alternate term for premillennialism).
basileia (βασιλεία, G932) — kingdom, reign; the broader category of which the millennium debate is one part — when and how is Christ's kingdom consummated?
• Revelation 20:1–6 — "They came to life and reigned with Christ for a thousand years."
• Matthew 24:36 — "But concerning that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father only."
• 1 Thessalonians 4:16–17 — "The Lord himself will descend from heaven...and we will always be with the Lord."
• Acts 1:11 — "This Jesus, who was taken up from you into heaven, will come in the same way as you saw him go into heaven."
• "Christians can disagree on the millennium and still share the same gospel — it's not a first-order doctrine. Christ's return is."
• "Premillennialists read Revelation 20 literally; amillennialists read it symbolically. Both read Romans 8 the same way — that's what matters."
• "The one millennial view that is absolutely wrong: that Christ is not returning at all."