Rev 20:1-6

THE ONE THOUSAND YEAR REIGN
The martyrs who died in the Reformation, “went up into heaven in a cloud” (Rev 11:12). This was the first resurrection.

The one thousand year period is the 2,300 years (days) from the abomination of desolation until the sanctuary will be cleansed (Dan 8:14), less the 1,290 years (days) when the sanctuary was “completely shattered” (Dan 12:7). 2,300 – 1,290 = 1,010 (1,000 years).

The 1,000 year reign began in the Reformation and will end when the Sanctuary is fully cleansed. During this time, the Martyrs reign with Christ; their blood speaks for their desire to reestablish the truth, the kingdom of heaven.
1 I saw an angel coming down out of heaven, having the key of the abyss and a great chain in his hand.2 He seized the dragon, the old serpent, which is the Devil and Satan, and bound him for one thousand years, 
Rev 20:2
and bound him for a thousand years – Satan does not create any new deceptions of the truth (though he remains the father of lies, John 8:44). Satan was the King of the fourth beast, and the deception of the beast ended after 42 months (193 to 1471).
3 and cast him into the abyss, and shut it, and sealed it over him, that he should deceive the nations no more, until the thousand years were finished. After this, he must be freed for a short time. 
Rev 20:3
and threw him into the abyss – this is not the lake of fire, but a holding place. The 6,000 demons who were cast out of the man in Luke 8:31, begged Jesus not to send them into the abyss, or “bottomless pit” – Rev 9:1

he would not deceive the nations any longer – the 1,000 year period that followed the Reformation is the undoing of Satan’s deceptions.

he must be released for a short time – after the truth is restored, and kingdom of heaven is cleansed, Satan will be released to deceive the world again.
4 I saw thrones, and they sat on them, and judgment was given to them. I saw the souls of those who had been beheaded for the testimony of Jesus, and for the word of God, and such as didn’t worship the beast nor his image, and didn’t receive the mark on their forehead and on their hand. They lived, and reigned with Christ one thousand years. 
Rev 20:4
then I saw thrones – from Dan 7:9, Dan 7:22, and Dan 7:26: “the court will sit for judgment.” The martyrs sit on thrones as the truth will be discerned.

I saw the souls – as explained in Rev 6:9, only the souls have resurrected. The bodily resurrection will occur at the last trumpet, when we shall all be changed (1 Cor 15:51).

they reigned for one thousand years – their blood speaks for the truth. They became a sacrifice like Christ, for the gospel, and they sit with Him on His throne, after resurrecting like Him.
5 The rest of the dead didn’t live until the thousand years were finished. This is the first resurrection. 
Rev 20:5
until the thousand years were completed – it seems that no significant amount of time follows the 1,000 year cleansing of the sanctuary, until Christ returns.
6 Blessed and holy is he who has 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 one thousand years. 
Rev 20:6
Blessed and holy is the one who has part in the first resurrection – they have already passed from judgment into eternal life. They have escaped the second death, the eternal death of those who are not redeemed, by the lake of fire (Rev 20:14).