Revelation, chapter 20:
01 Then I saw an angel coming down from heaven, holding in his hand the key to the abyss and a huge chain.
02 He took hold of the Dragon, the serpent of origins, who is the Devil, Satan, and chained him for a thousand years.
03 He threw him into the abyss, closing it on him; then he sealed it so that the Dragon would no longer lead the nations astray, until the thousand years came to an end. After that, he must be released for a little while.
04 Then I saw thrones: power to judge was given to those who came to sit on them. And I saw the souls of those who were beheaded because of the testimony for Jesus, and because of the word of God, they who did not bow down to the Beast and his image, nor receive his mark on their foreheads or hands. They came back to life and reigned with Christ for a thousand years.
05 The rest of the dead did not come back to life until the thousand years were over. This is the first resurrection.
06 Blessed and holy are those who share in the first resurrection! The second death has no power over them: they will be priests of God and of Christ, and will reign with him throughout the thousand years.
07 And when the thousand years have come to an end, Satan will be released from his prison,
08 he will go out to lead astray the people of the nations who are in the four corners of the earth, Gog and Magog, to gather them together for war; they are as numerous as the sand of the sea.
Christ’s resurrection ushers in the thousand-year period in which the righteous reign with Christ. Baptism brings humanity into close communion with God, with Jesus. It means becoming members of the body of Christ, true God and true man. It means receiving and being filled with the Spirit, with God’s love. There are three types of baptism: by water and Spirit, by desire and by blood. That is to say, even those who did not receive baptism in the Church, but lived such a communion of faith with God as to give witness to their lives offered for righteousness, received the Spirit of God who sustained them in trial, and likewise for those who desired baptism in the Church but died before receiving it. Baptism is indeed what is called: the first resurrection. It is at this moment that the human being is conformed to Christ, becoming a member of his body, animated by his breath of love. Then, the life of the baptized becomes a testimony of love, of trust in God’s forgiveness offered in Jesus Christ to the multitude. The righteous thus enter God’s time, the time that unites us to the life of Christ. This assures the believer of faith in Christ’s final victory over all evil and death. This faith, this confidence, will lead him to defy the world, to defy earthly rewards and honors that don’t last. All this will be of little value to him. His peace comes from his trusting relationship with God, and he places his life in God’s hands. These are the thousand years of peace with Christ that believers experience in every age, not a thousand earthly years, for Jesus explains to the apostles that they do not belong to the world:
Peace, I leave with you, my peace I give to you; not after the manner of the world do I give it to you (John 14:27).
If the world hates you, know that it hated me first. If you belonged to the world, the world would love what is its own. But you don’t belong to the world, because I chose you from the world; that’s why the world hates you. (John 15:18-19)
The Fathers of the Church often quote verse 4 of Psalm 90: “In your eyes, a thousand years are like yesterday; it is a day that is passing away, an hour in the night”, and also the words of St. Peter himself:
Beloved, one thing must not escape you: for the Lord, one day is like a thousand years, and a thousand years are like one day. (2 Peter 3:8)
St. Caesarius of Arles, in his homily 13 on the Apocalypse, explains:
When [in the Apocalypse] it is said that men are to be gathered for the great day, this great day represents all the time that elapses from the Lord’s passion to the end of the world.
The thousand-year period thus indicates the time inaugurated by Christ’s resurrection and the gift of the Holy Spirit at Pentecost. Indeed, when Saint Luke tells us of the descent of the Holy Spirit on the apostles on the day of Pentecost, he says this:
16 But what is coming was foretold by the prophet Joel:
17 It shall come to pass in the last days, saith God, that I will pour out my Spirit upon every creature: your sons and your daughters shall prophesy, your young men shall see visions, and your elders shall dream dreams.
18 Even on my servants and on my handmaidens I will pour out my Spirit in those days, and they will prophesy.
19 I will do wonders in heaven above, and signs on the earth beneath: blood, fire, a cloud of smoke.
20 The sun will be turned to darkness, and the moon to blood, before the Day of the Lord comes, a great day and manifest.
21 Then everyone who calls on the name of the Lord will be saved (Acts of the Apostles 2:16-21).
Joel’s prophecy speaks of the last days, and these last days began on the Day of Pentecost, fifty days after Christ’s resurrection. Indeed, God’s plan, the work of the six days of creation, was fulfilled by Jesus’ death on the cross: at that moment, his Spirit of eternal life was offered to mankind, and was poured out on the apostles on the day of Pentecost, to be passed on to mankind. To this day, the gift of the Holy Spirit continues to be transmitted to mankind by the successors of the apostles, each time fulfilling the creative gesture. Man is recreated by the gift of the Spirit, born to a new life, to the eternal life of filial relationship with God. The Church thus continues to accomplish Christ’s creative work by pouring out his Spirit on mankind. The day on which the baptized person is born to new life is the day of a thousand years, of the time when he or she lives with Christ.
The baptized person spiritually enters the kingdom of God by adhering to the divine life. While on earth, he lives a time of union with God in the filial relationship offered to him. This time is called “a thousand years” because it is already the premise of the eternal life we have entered through baptism. In chapter 6 of the letter to the Romans, Saint Paul explains that, through baptism, we are united to Jesus Christ and, having died with him to sin, we share in his resurrection. Unfortunately, just as in the life of Jesus, union with God will also give rise to hatred, jealousy and persecution, as Jesus predicted to the apostles: they will all die martyrs. Now, the word martyr means witness, witness to God’s love. This witness can be offered to the world by the righteous innocent who endures persecution, but it can also be revealed in the silent offering of one’s life lived in love of neighbor, family, children, friends and enemies in daily life. In this testimony, we must be faithful to the end, trusting to the end, that is, trusting in trials, because the righteous person unleashes jealousy, envy and rivalry in spite of himself. And that’s why Revelation announces that in the life of every righteous person, this time of first resurrection, which is given by the discovery of a life in deep communion with God the Creator, will also be brought to an end by the final unleashing of the devil, the enemy, for this cannot be without arousing attacks and persecutions. All of us in this world are put to the test, constantly faced with choices: for the good and love of our neighbor, or for our own profit at the expense of others. Yet every life is sacred, and the principle by which Jesus was condemned to death, the principle by which a righteous man was allowed to die, can never be acceptable:
Then one of them, Caiaphas, who was high priest that year, said to them, “You don’t understand anything; you don’t see what your interest is: it is better that one man should die for the people, and that the whole nation should not perish.” (John 11:50)
Every life is sacred, and injustice cannot be accepted under any pretext or motive. Respect for life must be exercised to the very end towards all forms of life: from the fetus to those who are near the end of their life, in a coma or in old age, destitute, powerless, poor. Harming life excludes us from life. Appropriating worldly goods at the expense of others excludes us from communion with others, from the source of joy, from the source of life. The end does not justify the means. Accepting evil, big or small, means cutting ourselves off from life. You cannot serve two masters, says Jesus in Luke 16:13: “No servant can serve two masters: either he will hate the one and love the other, or else he will cling to the one and despise the other. You cannot serve God and money at the same time.” Adherence to life must be total. Accepting evil means turning away from life. The experience of evil is a torment for the human being, and the only way out is to repent and ask for forgiveness; all evil must be rejected, so that we can embrace life.
The Fathers of the Church also gave us a rule of life regarding our attitude towards the transient goods of this world: consider yourselves as stewards of the goods of this world. Those who possess goods, as if they didn’t possess them, but manage them for the good of all. To appropriate something for oneself, to the detriment of others, means to appropriate the tree of life, to steal it, to break the relationship of trust and love, to prefer one’s life to the life of others, instead of sharing and preserving the life of the whole body by being one of its members. “Whoever loves his own life loses it; whoever separates himself from it in this world will keep it for eternal life” (John 12:25), Jesus tells us. Eternal life is the communion of love between members of the same body, the brotherly love that unites people and becomes an inexhaustible source of life and joy, where each is a source of joy and love for the other. Seeking this communion, welcoming this life as a gift from God, welcoming God’s presence in everyone means entering eternal life already on earth. This is expressed and realized in baptism, where man welcomes back the source of earthly paradise within himself, welcomes life as a gift from God, contemplates the tree of life where Christ is crucified and sees there the gift of God’s love offered to the multitude, he sees blood and water gushing from his side. “This is why the Father loves me: because I lay down my life, that I may receive it again. No one can take it from me: I give it of myself. I have the power to give it, I also have the power to receive it again: this is the commandment I have received from my Father” (John 10:18), Jesus tells us before he is arrested, and in these words he expresses the eternal love God has for us, the love he offers to all his children. Whoever takes the life of his neighbor for himself, for his own profit, whoever exploits and appropriates it, cuts himself off at the same time from this source of life, from the opportunity to discover joy and peace in the love of his neighbor. But the tree of life is always offered, the return is always possible, all we have to do is recognize what we have already received, recognize the love with which we are loved and draw anew from His forgiveness, from the renewed, eternal gift, to return to Him.
This is the first resurrection spoken of in Revelation, the entry into eternal life, into the love of God and neighbor through baptism and the acceptance of God’s life and forgiveness on this earth. A thousand years is like a day for God, a thousand years in God is like a breath, a moment of eternal happiness. So the thousand years spoken of in Revelation are not to be understood as years made up of 365 days, but as the time of each person’s life with God on this earth, the time of a life renewed by baptism and by the trusting, filial relationship rediscovered with God. It means entering God’s eternity now, by rediscovering his presence in our neighbors, whom we welcome as our brothers and sisters. Then the kingdom of God, Jesus the Christ, descends into our hearts and introduces us to communion and eternal joy, even if this is still marked by death, persecution and evil. Saint Paul tells us of this communion with Christ:
Who then can separate us from the love of Christ? distress? anguish? persecution? hunger? destitution? danger? the sword? Indeed, it is written: For your sake we are slaughtered all the time, treated like sheep for the slaughterhouse. But in all this we are the great victors, thanks to him who loved us. I am certain of it: neither death nor life, neither angels nor principalities, neither the present nor the future, neither powers, nor heights, nor depths, nor any other creature, nothing can separate us from the love of God which is in Christ Jesus our Lord. (Letter of Saint Paul to the Romans 8:35-39 ©AELF)
We share his victory over evil, a victory that is accomplished every time we show his merciful face to our persecutors, to our enemies, every time we forgive 70 times 7 times, we carry a reflection of his love into this world and the victory over evil is accomplished in us too, because evil, vengeance, hatred do not win our own hearts. When we do not respond to evil with evil, to offence with offence, it is Christ’s victory that is manifested in us, the enemy of man, evil is vanquished and no longer has any power over us. “Abide in me, as I in you” (John 15:4), Jesus tells us, he is the vine, we are the branches, the Father is the vinedresser and he makes us taste the fruit of the vine, he fills our cup with love.
And yet, in speaking to us of the vine, Jesus also announces that if we abide in him, like him we will be glorified, but this glory, which reveals to the world the love of God that dwells within us, is revealed in trial: “If they persecuted me, they will persecute you too” (John 15:20).
The parable of the vine, the branches and the vinedresser sums up the whole of human life, revealing how to abide in God so that our joy is perfect, and how the vinedresser leads us to bear fruit (The parable of the vine).
The time during which God allows the devil to act and test his faithful is related to the time of Christ’s passion on the cross.
25 It was the third hour (that is, nine o’clock in the morning) when he was crucified.
…
33 When the sixth hour (i.e. noon) came, darkness fell over the whole earth until the ninth hour.
34 And at the ninth hour, Jesus cried out with a loud voice: “Eloi, Eloi, lema sabactani?”, which is translated: “My God, my God, why have you forsaken me?” (Mark 15:25, 33).
The time during which the forces of evil are unleashed against him also becomes, proportionately, the time when each faithful person, when the Church is persecuted. So, in the life of God’s kingdom on earth, that is, in this time of love and communion with God and neighbor, there is also the time when the devil is unleashed, when by acting against the just, he reveals his true face. And by condemning the righteous, he condemns himself (see article The cup, the judgment), separating himself from the source of life.
Yet the Gospel shows us that evil, the devil, and Jesus’ enemies can do nothing against him, until he allows them to. The devil cannot stand up to Jesus and asks to be spared, to escape. Those who wish to harm Jesus’ life cannot. In Nazareth, for example, the crowd wanted to throw him off the cliff, but they couldn’t, because his hour had not yet come. And Jesus passed among them without anyone touching him. But when the time came, it was Jesus himself who ordered Judas to do what he had to do, and the devil entered him. It is Jesus who gives permission, who leaves the devil free to act against him, so that his love for mankind may be revealed to the world. He freely accepts to suffer the passion, to be crucified. This is when the Psalm “My God, my God, why have you forsaken me?” is fulfilled. It’s true, God leaves the forces of evil free to unleash themselves against the righteous. But this psalm is not one of despair; on the contrary, it is a psalm of confidence. Indeed, this psalm is usually recited at the moment of death, or in the presence of the deceased, for the verses that follow tell us of the assurance of resurrection: “You have answered me! And I proclaim your name before my brothers; I praise you in the assembly” (Ps 22:22-23). So, there is a moment when we are abandoned to death, and we must place our spirit in God’s hands, as Jesus did: “Father, into your hands I commend my spirit” (Luke 23:46). There is a moment when we let death approach, when we abandon ourselves, and when we can also perceive this as an abandonment on God’s part. But at the same time, we are called to proclaim our faith, like old Samuel who said: “Now, O sovereign Master, you may let your servant go in peace” (Luke 2:29). In reality, our spirit rests in God; we hand it over to him in trust, and he will preserve it from death and lead it to the springs of life, to the waters of life, as Psalm 23:1-3 says: “The Lord is my shepherd; I shall not want. He maketh me to lie down in green pastures. He leads me beside still waters and makes me live again” and in verse 4: “Though I walk through the ravines of death, I will fear no evil, for you are with me.” So Jesus walks the path of the righteous, delivered to death, but by reciting the prayer of the Psalm at a time when his enemies are raging against him, he testifies to his confidence in God’s response, who answers him and raises him from death, and reveals to the world his righteousness, calling out to all nations. (See the whole of Psalm 22, which describes in detail Christ’s passion, but also God’s response and salvation).
Through baptism, then, the faithful share in Christ’s death and resurrection, entering God’s eternity, represented by the thousand years, but still on earth, exposed to the attacks of the devil and the enemy, who test their love for God and neighbor, Finally, those who do not believe in love will have the proof of love, they will see it before their eyes, in spite of the evil they vow against it, a face of mercy and forgiveness appears to them. This time of a thousand years is indeed the time when, through baptism, we have already risen with Christ, already entered eternal life, we share his victory over evil, and since we are still on earth, we are subjected to the attacks of evil, just as Christ was delivered up to his passion. But like him, strengthened by his spirit, we do not give in to hatred or vengeance, and evil and death cannot triumph, cannot reach our hearts. Afterwards, there will also be the resurrection of the dead, of the bodies, and this victory will be dazzling in the eyes of all, and those who have accepted God’s gift and gift-gift will sit at his right hand. The word sit means that the righteous has become a judge, a judge who welcomes repentance and the request for forgiveness, a judge who gives grace and whose condemnation is solely the consequence of the choice of those who persist in opposing him and do not welcome his love, his clemency, for his forgiveness is always offered. Indeed, Jesus tells the apostles that they will sit with him (Matthew 24:21), and likewise announces that the righteous, those who have repented, will govern and judge the earth.
Texts from the Fathers
Tyconius, Commentaire de l’Apocalypse, Introduction, traduction et notes par Roger Gryson, Brépols, 2011, p.203-204, n.20 :
To make it clear what these thousand years are, he added: “This is the first resurrection”, obviously the one that brings us back to life through baptism, as the apostle says: “If you have been raised with Christ, seek the things that are above” (Colossians 3:2), and again: “As living men raised from the dead” (Romans 6:13). Sin, in fact, is death, as the same apostle says: “While you were dead through your trespasses and sins” (Ephesians 2:1). Just as there is a first death in the present life, because of sins, so there is also a first resurrection in the present life, thanks to the forgiveness of sins.
Augustine, The City of God 20, 6, 2 (latin text in Bibliothèque Augustinienne vol. 37, p. 209-211):
There are therefore two regenerations, and we have already spoken of them above: one according to faith which is accomplished now by baptism, the other according to the flesh which will be accomplished in incorruptibility and immortality by the great and last judgment; so there are also two resurrections: one “first”, which takes place now and is that of souls, which prevents them from falling into the second death; the other “second”, which is not of now, but will take place at the end of the age; it is not that of souls, but of bodies, and by the last judgment it sends some into the second death, others into the life which is free from death.
Augustine, Homelies the gospel of saint John 19, 13 (latin text in Bibliothèque Augustinienne vol. 72, p. 198-199):
“What about you, O soul? You were dead, you had lost your life; listen to the Father speaking through the Son. Arise, receive life, so that this life which you do not have in yourself, you may receive in him who has life in himself. So it is from the Father and the Son that life comes to you; then the first resurrection takes place, when you rise to participate in the life you don’t have, and through this participation you become alive. Resurrect from your death to your life, which is your God, and pass from death to eternal life.
Augustine, City of God, book 20, chapter 7:
The same evangelist speaks of these two resurrections in his Apocalypse, but in such a way that some of us, not having understood the first, have given in to ridiculous visions. This is what the apostle Saint John says: “I saw an angel coming down from heaven, having the key to the abyss and a chain in his hand, and he took the dragon, that old serpent called the devil and Satan, and bound him for a thousand years. Then, having thrown him into the abyss, he closed the abyss and sealed it over him, so that he would no longer deceive the nations, until the thousand years were over; after which he must be bound for a little while. I also saw thrones and people sitting on them, to whom the power to judge was given; with them, the souls of those who were slain for the testimonies they gave to Jesus and for the word of God, and all those who did not worship the beast or his image, nor receive his character on their foreheads or in their hands; and they reigned for a thousand years with Jesus. The others did not live until a thousand years had passed. This is the first resurrection. Blessed and holy is he who shares in it! The second death will have no power over them, but they will be priests of God and of Jesus Christ and will reign a thousand years with him” (Rev 20:1-5). Those to whom these words have given reason to believe that the first resurrection will be bodily, have above all adopted this opinion because of the number of a thousand years, in the thought that all this time must be like the Sabbath of the saints, where they will rest after the labors of six thousand years which will have elapsed since man was created and precipitated from the felicity of paradise into the miseries of mortal life, so that, according to this saying: “Before God, one day is like a thousand years, and a thousand years like one day” (2 Peter 3:8), six thousand years having elapsed like six days, the seventh, i.e. the last thousand years, will take the place of the Sabbath for the saints who will be resurrected to solemnize it. All this would be admissible up to a point, if we believed that during this Sabbath the saints will enjoy some spiritual delights, because of the Savior’s presence, and I myself was once of this sentiment (See Sermon 259). But as those who adopt it say that the saints will be in continual feasts, only carnal souls can be of their opinion. This is why spiritualists have given them the name of chiliastes (Kiliastas), from a Greek word that can literally be translated as millennia. It would take too long to refute them in detail; I prefer to show how these words from Revelation should be understood.
Our Lord Jesus Christ himself said: “No one can enter the house of the strong man and take away his possessions unless he first binds him” (Mark 3:27). By the strong man, he means the devil, because he has subjugated mankind, and by his possessions, the faithful, whom he had committed to impiety and crime. It was to bind this strong man that Saint John, according to the Apocalypse, saw an angel descend from heaven, holding the key to the abyss and the chain. And he took the dragon, that old serpent, whom we call the devil and Satan, and bound him for a thousand years; that is, he prevented him from seducing and subjugating those who were to be delivered. The thousand years can be understood in two ways: either because these things take place in the last thousand years, i.e. in the sixth millennium, the last years of which are now passing away to be followed by the Sabbath which has no evening, i.e. the rest of the saints which will never end, so that Scripture here calls a thousand years the last part of this time, taking the part for the whole; – or it uses this number for the whole duration of the world, thus employing a perfect number to mark the fullness of time. The number one thousand is the cube of ten, ten times ten making one hundred; but this is a flat figure, and to make it solid, multiply one hundred by ten and it makes one thousand. Moreover, if Scripture uses a hundred for an indefinite number, as when Our Lord promises those who leave everything to follow him that “they will receive a hundredfold from this life” (Mt 19:29; Mk 10:30), which the Apostle expresses by saying that a true Christian possesses all things, even though it seems that he has nothing (2 Cor 6:10), according to this saying again: “The world is the treasure of the faithful” (Proverbs 17:7 according to the LXX trans. LXX), how much more must the number of a thousand years signify universality? And this is the best meaning we can give to the words of the Psalm: “He has always remembered his covenant and the promise he made for a thousand generations” (Ps 105:8), i.e. for all generations.
Augustine, City of God, Book 20, 9, 1 (Bibliothèque Augustinienne vol. 37, p. 235):
“Therefore, now also the Church is the kingdom of Christ and the kingdom of heaven.”
Augustine, City of God, Book 20, 9, 2 (Bibliothèque Augustinienne vol. 37, p. 237):
For the souls of the just at death are not separated from the Church, which from now on is the kingdom of Christ. Otherwise, they would not be remembered at the altar of God in communion with the body of Christ.
Augustine, City of God, Book 20, 13 (Bibliothèque Augustinienne vol. 37, p. 255):
Thus in these three and a half years, the souls of those who were put to death for the testimony of Christ, those who will have previously come out of their bodies and those who will come out during this very last persecution, will reign with him until this mortal century ends and is passed into that kingdom where there will be no death.
Augustine, City of God, Book 20, 7, 2 (Bibliothèque Augustinienne vol. 37, p. 214):
Or undoubtedly [Saint John] used a thousand years for all the years of this century, with a view to marking by a perfect number the very fullness of time. The number one thousand is the cube of ten, ten times ten making one hundred; but this is a flat figure, and to make it solid, you have to multiply one hundred by ten and that makes one thousand. (…) So this is the best meaning we can give to the words of the psalm: “He has always remembered his covenant and the promise he made for a thousand generations”; that is, for all generations.
Cesarius of Arles, Homily 18 in L’Apocalypse expliquée par Césaire d’Arles, Les Pères dans la foi, DDB, 1989, Paris, p.144-145-149 :
The bride of the Lamb is the Church. “And it was given to her to clothe herself in fine linen, bright and pure” (Rev 19:8). Indeed, fine linen “is the good works of the saints” (Rev 19:8); it was given to her to clothe herself in her works, as it is written: “Let your priests clothe themselves in righteousness” (Ps 131:9). All these,” he says, “lived and reigned with Christ a thousand years” (Rev 20:4), i.e. in the present age. And he rightly says, all the survivors and the souls of the saints: that is, those still living in this world and those who have already left this life and reign with Christ. He said: “They have reigned”, in the perfect tense, as in: “They have shared my garments”, (Ps 21:19), for he should have said: “They will reign”. Indeed, to show that these thousand years are in this life, he says: “This is the first resurrection” (Rev 20:5). This is the resurrection into which we are resurrected by baptism, as the Apostle says: “If you have been resurrected with Christ, then you are seeking a new life.
resurrected with Christ, seek the things that are above” (Col 3:1), and again: “as those who have come back from death” (Rom 6:13). Indeed, sin is death, as the Apostle says: “While you were dead because of your trespasses and sins” (Eph 2:1). And just as the first death in this life is death by sin, the first resurrection in this life is the forgiveness of sins. “Blessed and holy is he who shares in the first resurrection. That is, who will have preserved what he was born again to in baptism. “The second death has no power over him”, that is, he will not suffer eternal torment. “But they shall be priests of God and of Christ and shall reign with him a thousand years.” As he wrote this, the Spirit revealed to him that the Church would reign a thousand years in this century until the end of the world. Clearly, we must not doubt the eternal reign, when even in the present time, the saints reign. Indeed, it is well said that they reign who, with God’s help, lead themselves and others well, even in the midst of worldly trials. When he says that they reigned a thousand years, understand the present time during which it is rightly said that the saints reign; because with God’s help they conduct themselves in such a way that they cannot be overcome by sin. And to make this clear, he continued: “This is the first resurrection” (Rev 20:5). For as the first death in this life is death by sin, so the first resurrection is through the forgiveness of sins. “Blessed and holy is he who shares in the first resurrection” (Rev 20, 6), i.e. who will have preserved what he received by being reborn through baptism. But when he says that the Church will reign for a thousand years, he means in this time until the end of the world. Hence it is clear that we must not doubt the eternal reign: even in the present time, the saints reign. Indeed, it is rightly said that they reign, those who, with God’s help, lead themselves and others well, even in the midst of the trials of the world.
Saint Thomas Aquinas confirms the value of Augustine’s interpretation, in his Commentary on Pierre Lombard’s Sentences. The text reproduced here is translated in French by J. Ménard and published on the Institut Docteur Angélique website:
Book 4, distinction 43, question 1, article 3, quaestiuncula 1 and 2: On the occasion of these words, as Augustine relates in The City of God, book 20, certain heretics asserted that a first resurrection of the dead should take place, so that they might reign a thousand years with Christ on earth. They were therefore called chiliastes or millenarians. In the same place, Augustine shows that these words are to be understood in another way, namely, of the spiritual resurrection by which men are raised from their sins by the gift of grace. But the second resurrection is that of bodies. Now, the Church is called the kingdom of God: in it, not only the martyrs reign with him, but also the other elect, so that the whole is understood from the part. Or all reign with Christ in glory. But special mention is made of the martyrs, because they in particular reign once dead, having fought to the death for the truth. Now, the number one thousand does not signify a specific number, but it designates the totality of the time that now exists, during which the saints reign with Christ, for the number one thousand designates universality more than the number one hundred, because the number one hundred is formed from the repetition of the ten, whereas the number one thousand comes from the multiplication of ten by ten by ten. Similarly, Ps 104:8 says: … of the commandment he has given for a thousand generations, i.e. for all of them.
As Augustine says, in the Book on 83 Questions, the ultimate age of mankind, which begins with the advent of the Lord until the end of the century, is uncertain as to the number of generations counted, just as old age itself, which is the ultimate age of man, does not have a time determined according to the measure of the other [ages], since sometimes it alone possesses as much time as the other ages. The reason for this is that the determined number of time to come can only be known by revelation or natural reason. Now, the time before the resurrection cannot be counted by natural reason, because the resurrection and the end of heaven’s movement will occur at the same time, as has been said. Now, the number of all that is foreseen as to come by natural reason, according to a determined time, is taken from the movement. But the end of the sky’s movement cannot be known from its motion, for, this being circular, it can thus by its very nature last perpetually. So the time that will exist until the resurrection cannot be counted. Nor can it be known by revelation, so that all may always be attentive and prepared for Christ’s arrival. For this reason, [the Lord] replied to his disciples who asked him about it (Acts 1:7): It is not for you to know the times and moments that the Father has established by his sole authority. By this, as Augustine says in The City of God, Book 18, he has annulled the calculation of all those who counted on their fingers, and commands them to cease. Indeed, since he did not wish to indicate this to the apostles, he will not reveal it to others. So all those who tried to count the time in question found themselves speaking falsely. Indeed, as Augustine says in the same place, some have said that forty years could elapse between the Lord’s ascension and his final coming, others fifty, others a thousand: their falsity is manifest. The same will be true of those who never stop counting.
Saint Thomas Aquinas, Summa contra Gentiles
Book 4, question 83: As for the words of the Apocalypse about the thousand years and the first resurrection of the martyrs, this resurrection must be understood as the resurrection of souls, resurrected from sin. This is the meaning of Saint Paul’s words to the Ephesians: Rise from the dead and Christ will enlighten you. The thousand years signify the time of the Church, during which the Martyrs, along with the other saints, reign with Christ, both in the Church here below, called the kingdom of God, and in the heavenly homeland as far as souls are concerned.
See also the article The 3 times of Revelation
Saint Thomas Aquinas, Treatise on the Articles of Faith
First part, article 5: The sixth error is that of Cerinthus, who affabulates by saying that after the resurrection there will be on earth a reign of a thousand years, during which men will have the carnal pleasures of the belly and voluptuousness. St. Matthew teaches against them, ch. 22:30: “that after the resurrection they will neither marry nor be married.” There are also those who say that after the resurrection of the dead, the world will remain in the same state as it is now. It is written against them in Revelation, ch. 21:1: “I have seen a new heaven and a new earth.”
Saint Thomas Aquinas, Commentary on the First Letter to the Corinthians
The apostle therefore says that we shall all rise, but how? In a moment (1 Cor 52); and with this expression he refutes the error of those who think that the resurrection will not take place simultaneously for all. They say that the martyrs will rise before the others for a thousand years; that Jesus Christ will then descend with them and possess with them a temporal kingdom in Jerusalem for a thousand years. This was the opinion of Lactantius. Its falsity is clear to see, for we shall all be resurrected in a moment, in the twinkling of an eye. This passage also destroys another error of the same Lactantius, who claimed that the judgment would last for an interval of a thousand years. This opinion is still false, since there will be no measurable interval of time, but that in a moment, etc., the judgment will last.
For an extensive treatment of the theme of millenarianism, see Cyril Pasquier‘s doctoral thesis, Approches du millénium Une christologie de l’histoire, Université de Fribourg, 2018.