The Millennium is a most mysterious time period to grasp. Up to this point, in summary, Jesus has raptured His believing church up to heaven, thus instigating the 7 year, Great Tribulation Period. During the Tribulation, a great revival took place as a result of the 144,000 believing Jews and the two witnesses evangelizing across the globe. Many of them would die at the hands of evil men when they refused to take the mark of the Beast. At the end of Jesus' directing judgments on sinful mankind for those seven years, Jesus returned to kill the vast army gathered at Armageddon. He cast the Beast and False Prophet into the lake of fire, or hell. There are still the 144,000 sealed Jews and some other people left on the earth when Jesus returned with us, His bride. Interesting, we left heaven in our glorified bodies to return to earth with Him. Soon, He will create a new heaven and a new earth. Currently, in Chapter 20, God directs an unnamed angel to seize the devil and cast him into the bottomless pit, a spiritual prison, for 1000 years, ushering in a time of unparalled peace on the earth. Can you imagine life without Satan's influence?
We raptured souls will reign with Christ during the Millennium. We are tasked with enforcing rules and righteousness, encouraging folks to live rightly. The saints will serve Jesus in various capacities. Our faithfulness while on earth today will determine the extent of our glorious responsibilities during the kingdom age (Matt. 25:14-30; Lk. 19:11-27). People will still have their humanity and fleshly tendencies, even without Satan's influence. Mysteriously, Satan is allowed to be loosed after the 1000 year period, where he deceives the nations again and incites a rebellious riot against Jesus, and I would have to assume us, as well, since we are true representatives and ambassadors for Christ. All the while, humans will be propagating and multiplying at an unfathomable rate, considering it seems no one actually dies during this time period; therefore, Satan is able to gather a massive army to march against Israel. Fire comes down from heaven to devour the army and Satan is thrown into hell for eternity, never to be loosed again. These events prove once and for all that it is absolutely impossible for man to change his heart within his own ability and power. Even when there is heaven on earth and everything is perfect, mankind, left to his own devices, will fall away and be led astray. Fortunately, what is impossible for man is possible for God. We cannot overcome our flesh without the amazing grace of God. This describes our most desperate position of needing a Savior, because there is absolutely no way for us to save ourselves. If it weren't for the blood of Jesus, we would all be doomed to hell because that is what sin deserves.
There are two resurrections mentioned. The first involves all saved people and is more of a parade over a time period. It started with Jesus being resurrected along with some others that first Easter Sunday. It includes the dead in Christ, those Tribulation saints that gave their lives in service. Old Testament saints are also raised at this point (Dan. 2:1-3). So, the first resurrection raises all saved people to help co-reign with Christ during the Millennium.
The second resurrection involves all of the unsaved people and happens after the 1000 year period. They will all stand before Jesus to be judged. This contrasts saved people, who are judged upon salvation since Jesus paid the price for our sins on the cross. The depth of what He did for us will remain a mystery until we're in heaven. He died for each of our specific sins individually. The dead stand before God and the books are opened. These books include the Bible as the infallible Word of God. The Book of Life contains the names of those people that have been saved by the blood of Christ. Another book includes all deeds done in this life. God keeps a record and judges each deed accordingly. Hell will have varying degrees of punishment, just as heaven will have varying degrees of reward (Matt. 11:20-24). If you deliberately disobey after knowing the truth, you will be punished more harshly than one who doesn't know the truth. There will be no arguing at the throne of judgment. People will stand there speechless (Rom. 3:19). All people in the second resurrection must face the second death, which is hell. Satan and sin are also thusly judged. Human rebellion is put down. Now God can usher in a new heaven and a new earth.
In the Millennial Kingdom, there will be peace for men and animals alike. Each person is suited to their best job. Perfect efficiency and joy fill the earth. But still, mankind drifts into selfishness. Our greatest application here is dealing with our heart's unrest and dissatisfaction. "Oh, if only I could have that...or, as soon as I get this thing straightened out, I'll....or, I'm going to be happy as soon as this stuff eases up...or, as soon as I get this cleaned up....or, when I get into a better situation." You can't chase happiness and win. Either you never get there or when you do get there, it isn't near as fulfilling as you hoped and dreamed. What if you could just be happy right where you are, sort of like God loving you just as you are right now? Right in the middle of all your junk? In the current mess you're in? Psalm 144:15 says, "Happy is that people whose God is the Lord." When God is your "thing", that's happiness. What is your "thing" or big deal? What are you into? Seek the Lord and draw close to Him. Live forth out of your relationship with Him. Allow Him to be present and in the center of all your activities. Be done with worldly pursuits that are simply temporary fixes. Make God your big deal. Be free of pursuing vain things. Don't go chasing waterfalls. You can be happy right in the middle of your stuff, right now, as you live in close relationship with the Lord. As you walk with Him over time, He develops His character in you, and you'll notice your desires and perspectives changing to align with His. That's happiness.