And I saw thrones, and they sat upon them, and judgment was given unto them: and I saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and who had not worshiped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years.
All Commentaries on Revelation 20:4 Go To Revelation 20
Augustine of Hippo
AD 430
that is, the souls of the martyrs not yet restored to their bodies. For the souls of the pious dead are not separated from the Church, which even now is the kingdom of Christ; otherwise there would be no remembrance made of them at the altar of God in the partaking of the body of Christ, nor would it do any good in danger to run to His baptism, that we might not pass from this life without it; nor to reconciliation, if by penitence or a bad conscience any one may be severed from His body. For why are these things practised, if not because the faithful, even though dead, are His members? Therefore, while these thousand years run on, their souls reign with Him, though not as yet in conjunction with their bodies.