A first resurrection suggests at least a second. The verse clearly says the second occurs one thousand years after the first. That verse 6 states that death has no power over those in the first resurrection strongly indicates that death will have power over those in the second. The second resurrection, therefore, must be a resurrection to physical life. Verse 6 also repeats from verse 4 that those in the first resurrection will reign with Christ. This means that His government is established, functioning, and executing judgment, among other things.
John W. Ritenbaugh
The Final Harvest
Those who never had an opportunity to learn God's way will be resurrected after the Millennium. "But the rest of the dead did not live again until the thousand years were finished" is parenthetical and does not refer to the first resurrection, but to a second resurrection.
Basic Doctrines: Eternal Judgment
Only the just, the righteous, will rise at Christ's second coming. God will raise the martyred saints to eternal life, but the unjust dead will not be resurrected until the end of this period. If we have the Holy Spirit dwelling in us when we die, we will be resurrected through the power of that same Spirit at that time (Romans 8:9, 11, 14). In addition to the dead in Christ, those who are true Christians at His coming will rise in the first resurrection. The Feast of Trumpets celebrates the second coming of Jesus Christ to intervene in world affairs, resurrect the firstfruits, and establish God's Kingdom on earth (Matthew 24:30-31; Revelation 11:15).
Martin G. Collins
Basic Doctrines: The First Resurrection
The first part of verse 5 inserts a parenthetical statement that refers to a second resurrection, described in verses 11-15. After the Millennium, God will raise up to physical life all those who have never had an opportunity for salvation. Christ will judge all those who lived throughout human history yet have not been called. Ezekiel 37:1-14 prophesies of God resurrecting all Israel. At the same time (see Matthew 12:41-42), He will raise all the Gentiles and extend to them the same offer He does to Israel (Romans 2:7-11; I Timothy 2:4). If they satisfy God's judgment, He will at some point grant them eternal life and give them spiritual bodies (I Corinthians 15:44-49).
After all have had their opportunity, God will perform still a third resurrection. Those who will not repent of their rebellion against the Almighty will be raised to physical life and cast into the Lake of Fire, which provides a merciful, permanent death (see Matthew 25:41).
Martin G. Collins
Holy Days: Last Great Day
"This is the first resurrection" in Revelation 20:5 refers back to the events of verse 4, which describes those who are raised to immortality at Christ's second coming to become rulers with Him as kings and priests on the earth during the Millennium. The Bible nowhere says God will resurrect all the dead in the same resurrection. The apostle Paul affirms that both the "just" and "unjust" will be resurrected (Acts 24:15), and Jesus speaks of a "resurrection of life" and a "resurrection of condemnation" or judgment (John 5:28:29). However, these do not occur simultaneously. God has an orderly plan whereby He resurrects different groups of people at different times, "every man in his own order" (I Corinthians 15:23-24). This implies a succession of resurrections. Regarding the resurrection of the unjust, "the rest of the dead," who have not understood God's way of life, they must wait in their graves until the thousand years are over.
Martin G. Collins
Basic Doctrines: The Second Resurrection
Other Forerunner Commentary entries containing Revelation 20:5:
1 Samuel 16:13
1 Corinthians 2:2
1 Corinthians 15:23
1 Peter 2:7-10