The 1,000 year millennial reign of Christ on earth is a period of peace and rest when the curse brought on the world by the fall of Adam and Eve is partially reversed. The period is prophesied by Isaiah verses 65:25 and 11:6-7
[Isa 65:25 KJV] 25 The wolf and the lamb shall feed together, and the lion shall eat straw like the bullock: and dust [shall be] the serpent's meat. They shall not hurt nor destroy in all my holy mountain, saith the LORD.
[Isa 11:6-7 KJV] 6 The wolf also shall dwell with the lamb, and the leopard shall lie down with the kid; and the calf and the young lion and the fatling together; and a little child shall lead them. 7 And the cow and the bear shall feed; their young ones shall lie down together: and the lion shall eat straw like the ox.
Many people have not heard of the 1,000 year reign of Christ, known as the Millennium, or they think that it is not literal. However from the earliest times Christians have believed in the literal return of Christ to rule on the earth from Jerusalem. The main bible reference for this is Revelation 20: 1 - 10.
Jesus will literally return to the Mount of Olives in Jerusalem as the disciples were told he would do:
[Act 1:11 KJV] 11 Which also said, Ye men of Galilee, why stand ye gazing up into heaven? this same Jesus, which is taken up from you into heaven, shall so come in like manner as ye have seen him go into heaven.
This will be a fulfillment of the prophecy in Zechariah:
[Zec 14:3-4 KJV] 3 Then shall the LORD go forth, and fight against those nations, as when he fought in the day of battle. 4 And his feet shall stand in that day upon the mount of Olives, which [is] before Jerusalem on the east, and the mount of Olives shall cleave in the midst thereof toward the east and toward the west, [and there shall be] a very great valley; and half of the mountain shall remove toward the north, and half of it toward the south.
Satan will be cast into a bottomless pit for 1,000 years and Christ will rule on earth with his saints.
[Rev 20:1-4 KJV] 1 And I saw an angel come down from heaven, having the key of the bottomless pit and a great chain in his hand. 2 And he laid hold on the dragon, that old serpent, which is the Devil, and Satan, and bound him a thousand years, 3 And cast him into the bottomless pit, and shut him up, and set a seal upon him, that he should deceive the nations no more, till the thousand years should be fulfilled: and after that he must be loosed a little season. 4 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 which had not worshipped 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.
Literal not symbolic
The early church believed in the literal thousand year reign of Christ on earth. Only later in the 2nd and 3rd centuries did the church start to believe that this period was only symbolic. Below are some of the early church father's writings on the subject
Papias was was a Bishop of Hierapolis (modern Pamukkale, Turkey), and author who lived c. 60– c. 130 AD. According to Irenaeus, our earliest witness, Papias was "a hearer of John (the apostle) and a companion of Polycarp, a man of primitive times." In other words he was taught by John, the disciple of Jesus, himself. We only have fragments of what other writers had to say about Papias. Eusebius of Caesarea c260 - 340AD was a critic of Papias but this fragment shows that Papias was a believer in a literal 1,000 year reign of Christ
Attribution. Michel Wolgemut, Wilhelm Pleydenwurff (Text: Hartmann Schedel), Public domain, via Wikimedia Commons
"The same writer gives also other accounts which he says came to him through unwritten tradition, certain strange parables and teachings of the Savior, and some other more mythical things. To these belong his statement that there will be a period of some thousand years after the resurrection of the dead, and that the kingdom of Christ will be set up in material form on this very earth. I suppose he got these ideas through a misunderstanding of the apostolic accounts, not perceiving that the things said by them were spoken mystically in figures." Ecclesiastical History 3.39.1-16
Epistle of Barnabas
Attribution. Gerhard Haubold, CC BY-SA 3.0 <https://creativecommons.org/licenses/by-sa/3.0>, via Wikimedia Commons
The author of the letter is unknown. Jerome, Clement of Alexandria, and Serapion of Thmuis held that the biblical Barnabas (Acts 11-15; Gal. 2) wrote the letter. The writer of the Epistle of Barnabas (cir. 117/132 AD ) held to the idea that after six thousand years of history that would correspond to six days of creation, there would be a seventh day “sabbath” rest which would last one thousand years. The following is from the Epistle of Barnabas:
"Attend, my children, to the meaning of this expression, “He finished in six days.” This implieth that the Lord will finish all things in six thousand years, for a day is with Him a thousand years. And He Himself testifieth, saying, “Behold, to-day will be as a thousand years.” Therefore, my children, in six days, that is, in six thousand years, all things will be finished. “And He rested on the seventh day.” This meaneth: when His Son, coming again, shall destroy the time of the wicked man, and judge the ungodly, and change the sun, and the moon, and the stars, then shall He truly rest on the seventh day." The Epistle of Barnabas 15.4 in op. cit. The Ante-Nicene Fathers vol. 1. 146.
Many others in the early church believed the same thing. For example, Irenaeus, Justin Martyr and Hippolytus of Rome. For more information read "Pre-Millennialism and the Early Church Fathers" by Bob DeWaay. The web address is https://cicministry.org/scholarly/sch008.htm.