So since there will still be people with earthly bodies that means that Sin will still exist during those 1000 years especially if the Lord still permits procreation at that time. Yea I'm gonna have to study this for my self to understand this more cause this is very interesting to me.
There are various expressions in the Old Testament prophets that would make one think marrying and taking in marriage and having babies is going to continue through Christ's future "thousand years" reign, but those are really expressions. (see Isa 11:8-9; Isa 65:20; Zech 8:3-5 for example).
In Matthew 22:30 our Lord Jesus said those of the resurrection neither marry nor take in marriage, "... but are as the angels of God in heaven." So is that only about those of His elect that will reign with Him? No.
Recall John 5:28-29 about the wicked dead that are resurrected at Christ's coming as the "resurrection of damnation." If the damned are raised from the dead also per that, are they given new flesh bodies? No, for that would be a theory of reincarnation which God's Word does not agree with.
Here in Isaiah 25 is where Apostle Paul was pulling from when he taught the 1 Corinthians 15 idea of death being swallowed up in victory...
Isa 25:1-9
1 O LORD, thou art my God; I will exalt Thee, I will praise Thy name; for Thou hast done wonderful things; Thy counsels of old are faithfulness and truth.
2 For Thou hast made of a city an heap; of a defenced city a ruin: a palace of strangers to be no city; it shall never be built.
These first section of verses actually point to the events of the last days with Christ's coming and God's consuming fire upon the earth on the Day of The LORD. That is when He will in final make this symbolic "palace of strangers to be no city", destroying the Rev.17-18 Babylon Harlot "great city".
3 Therefore shall the strong people glorify Thee, the city of the terrible nations shall fear Thee.
This is about the future bowing to Christ as Lord during His future thousand years reign for as written all knees will bow to Christ and confess Him as Lord (Philippians 2:10-12; Romans 14:11).
4 For Thou hast been a strength to the poor, a strength to the needy in his distress, a refuge from the storm, a shadow from the heat, when the blast of the terrible ones is as a storm against the wall.
5 Thou shalt bring down the noise of strangers, as the heat in a dry place; even the heat with the shadow of a cloud: the branch of the terrible ones shall be brought low.
The wicked's "storm against the wall" is pointing to the end of days just prior to last day when God's consuming fire will come upon the earth to end this present world (see also latter section of Hebrews 12 and 2 Peter 3:10).
6 And in this mountain shall the LORD of hosts make unto all people a feast of fat things, a feast of wines on the lees, of fat things full of marrow, of wines on the lees well refined.
Per the end of Zechariah 14, we are shown leftovers of the nations that will have come upon Jerusalem against Israel on the last day of this present world, on that Day of The LORD. We're shown not all of them will be consumed on that day, and the leftovers of the nations will then be required to go up to Jerusalem to worship The KING, and keep the feast of tabernacles. There's this feast of Isaiah 25 that it's pointing to, and it will be for all the nations, even the leftovers, and not Christ's elect only. (yet there will be literal separation between Christ, His elect and those 'goats' of the rebellious nations). Within that Zech.14 Scripture, we are also shown what will happen to the nations in that future time that refuse to come up to Jerusalem to worship Christ and keep the feast. There will be no rain upon their lands.
So will there still be rebellion by the nations even after... Christ's future return? Yes. but only during that thousand years.
7
And He will destroy in this mountain the face of the covering cast over all people, and the vail that is spread over all nations.
What "face of the covering cast over all people"? What "vail that is spread over all nations"? That is about the covering and veil of our fleshy bodies, which were given us to serve as a bounds between our earthly world and the Heavenly where He and His dwell. This is revealed even more so with the following, "He will swallow up death in victory" idea which Apostle Paul quoted...
8
He will swallow up death in victory; and the Lord GOD will wipe away tears from off all faces; and the rebuke of His people shall He take away from off all the earth: for the LORD hath spoken it.
In that day all peoples and nations will be in the "spiritual body" type, not just Christ's elect, for He said there "all people" and "all nations". (yet there will still be a difference between those in Christ of the "first resurrection" unto eternal life and the spiritually dead souls with spiritual bodies still subject to the later "second death" of Rev.20. Apostle Paul covers that in 1 Cor.15, but some of it must be understood from the Greek; one can use a simple Strong's for that).
That is also when God shall remove the rebuke of His people, His chosen of Israel, from off this earth (many will be surprised in that time who all that will mean too, for they are not all Israel that are of Israel - Rom.9).
So we see that Apostle Paul in 1 Cor.15 was not only talking about Christ's elect still alive at His coming being 'changed' at the "twinkling of an eye" on that "last trump", but all people, and all nations too. That idea of God swallowing up death in victory He will do for all peoples on the last day of this world (except Satan's host of 7,000 on earth that will be destroyed on that last day per Rev.11).
9 And it shall be said in that day, "Lo, This is our God; we have waited for Him, and He will save us: This is the LORD; we have waited for Him, we will be glad and rejoice in His salvation."
(KJV)
By that point God's Salvation through His Son will have literally come upon this earth, and He will literally rule as KING over all peoples and nations at that time. Those of His elect will be saying this, "Lo, This is our God: we have waited for Him... ."
What's truly amazing is how this reveals the goats during Christ's thousand years reign will still... refuse Him and rebel by not going up to Jerusalem to worship Him and hold the feast of tabernacles per the end of Zech.14. All will 'know' The LORD in that future thousand years, including the wicked. In Rev.3:9 our Lord Jesus pointed to how those of the synagogue of Satan will even be made to bow in worship to Him at the feet of His elect. So all souls in that time will profess Christ Jesus is indeed King of kings, and Lord of lords, but many of the wicked will still refuse to accept Him into their hearts.
One may call the following supposition, my opinion based on all this. But I assure you, the above is not supposition, nor my opinion, but a revealing directly from God's Word.
How will our Heavenly Father be Just in destroying the wicked of the nations that will choose to follow Satan still at the absolute end, i.e., after Christ's thousand years reign when Satan is loosed one final time to go tempt the naitons? (Rev.20:7-15).
In that future time all peoples, including the 'goats' of Matt.25, will 'know' God and His Son Jesus Christ. None will have excuse in that time to not believe on Him. Christ will literally reveal Himself to all as Lord and King so all knees will bow and 'confess' Him as Lord. With Satan locked in his pit during that time, those will not even be able... to be deceived against Christ as Lord and King. So how could many of the wicked still refuse Him then once He is revealed to them directly?
The reason is, it all goes back to Satan's sin in the beginning, in coveting God's Throne for himself (Isaiah 14). Satan's followers abide by his lie that they can become their 'own' gods. They don't want 'any' authority over them, they don't even want God to exist because of Satan's deceiving them. For this reason, I believe the wicked who will still refuse Christ Jesus in that future time, they themselves will choose to go into the "lake of fire" and perish with Satan. God will destroy them because that's what they will choose for themselves.
So does this show sin will still be active for the 'goats' in Christ's future Millennial reign? Yes. And this is why our Lord Jesus and His elect will rule with that "rod of iron" as written (Psalms 2; Rev.2:27; Rev.12:5; Rev.19:15).