A thousand years. Christian apologists, explaining the delay in the return of Christ to the world, appealed to Ps. 90: 4—in the sight of God a thousand years are but as yesterday (2 Pet. 3: 8). Rev. (17: 1–18: 24) expected the End quite soon, after which there would be a millennium. In this time faithful Christians would reign together with Christ (Rev. 20: 1–6), and then Satan would be allowed a final assault before being banished for ever into the lake of fire and brimstone (20: 7–14).
‘Millennium’ is often used to refer to the era of total bliss (beyond the thousand years of Revelation) where God reigns for eternity.