"Then I saw an angel coming down from heaven, holding the key of the abyss and a great chain in his hand. And he laid hold of the dragon, the serpent of old, who is the devil and Satan, and bound him for a thousand years; and he threw him into the abyss, and shut it and sealed it over him, so that he would not deceive the nations any longer, until the thousand years were completed; after these things he must be released for a short time.
Then I saw thrones, and they sat on them, and judgement was given to them And I saw the souls of those who had been beheaded because of their testimony of Jesus and because of the word of God, and those who had not worshipped the beast or his image, and had not received the mark on their forehead and on their hand; and they came to life and reigned with Christ for a thousand years. The rest of the dead did not come to life until the thousand years were completed. This is the first resurrection.Blessed and holy is the one who has a part in the first resurrection; over these the second death has no power, but they will be priests of God and of Christ and will reign with Him for a thousand years."
This passage is a rather controversial one, so let's take it bit by bit. First of all an angel comes down from heaven and binds Satan (v1-3). This is similar to Jesus' description of his binding of a "strong man" (Matthew 12:29, Mark 3:27) but it is far more extreme, so perhaps this should be seen as the culmination of what Jesus came to accomplish at his first coming. Satan's defeat is now total, he is completely bound and unable to have any control over "the nations".
In verse 4, we see thrones, probably a reference to the "elders" from the scene in heaven (Rev 4:4). There are 24 elders, 12 for the disciples of the church and 12 for the tribes of Israel, so these thrones are a symbol of victory for all of God's people, New and Old testaments. A kind of judgement over the rest of humanity is then given to them, but what kind? It involves them coming to life and reigning "with Christ" for a period of one thousand years. In verse 5, it is referred to as "the first resurrection" and in verse 6 it refers to the resurrected believers as "blessed and holy... priests of God and Christ".
Now, why is the term "first" used? 'First', as opposed to 'second' in Revelation means "pertains to the fallen era of mankind" (first creation), rather than "pertains to the new restored era of mankind' (second creation). So there is something fallen, something carnal about this judgement of mankind that God's people exercise in the millennium. Also, why "priests of God and of Christ"? Priests sacrifice animals and then consume the offerings.
Consider John 5:64, "He who eats My flesh and drinks My blood has eternal life, and I will raise him up on the last day." So in the millennium, believers will eat the flesh that Jesus eats and drink the blood that he drinks. If we also take into consideration Malachi 4:3, ""You will tread down the wicked, for they will be ashes under the soles of your feet on the day which I am preparing," says the LORD of hosts", then we have the nature of this millennial reign with Christ.
Believers will be resurrected as zombies along with Christ and will harvest mankind for a thousand years of judgement on the earth. I call this position "Zombie-Millennialism".