Revelation 20:5-8

5 The remainder of the dead were not restored to life again until the thousand years were completed. This is the first resurrection. 

6 Blessed (happy, to be envied) and holy (spiritually whole, of unimpaired innocence and proved virtue) is the person who takes part (shares) in the first resurrection! Over them the second death exerts no power or authority, but they shall be ministers of God and of Christ (the Messiah), and they shall rule along with Him a thousand years.

Notice here to that we minister to people for a thousand years. Once again we see that there are still people, in human form, around after Jesus returns to the earth. We will not rule and judge as earthly rulers do now. We will rule and judge as Jesus does, as a servant, full of grace and love. We will have the servants towel on as we minister to the needs of those who were mistreated and under bondage for so long, John 13.   

7 And when the thousand years are completed, Satan will be released from his place of confinement, 

8 And he will go forth to deceive and seduce and lead astray the nations which are in the four quarters of the earth--Gog and Magog--to muster them for war; their number is like the sand of the sea.

Jesus is still ruling with an Iron Rod when satan is released, so Jesus is allowing these people to be deceived and gathered by satan. Why would our Lord allow such a thing? Just think of people today and you will see. There will be millions of people who never were killed during the Great Tribulation and who never took the mark of the beast. They will be allowed to live in the glory of our Lord. Yet just as with a lot of people today who get something for nothing, there will be many of them who will be spoiled and ungrateful. Not all of them, but we are told that many of them will be. So Jesus allows satan to be released and He allows these people follow him to be corrected. Satan is allowed to bring harm to these people’s flesh, so that their souls may be saved. We can see that our Father does this now, 1 Corinthians 5:5 and 2 Corinthians 12:7. Satan will not have a free will to do whatever he wants. Just as now, our Father will only allow satan to do what He wants him to do. 

Just think of how the population of the earth will grow when there is no war, disease, plagues, or famines for a 1000 years! It will be a wonderfully peaceful time to be alive and the population of the world will explode. Millions of people will have lived under Jesus, yet they will not have wanted to live under Him and when satan is loosed they will get their chance to rebel. Sounds crazy I know, but that is exactly what they will do. Yet Jesus will get them back. Jesus will not lose any that He has been given and He has been given all John 17:2 & 6:39. Everyone will acknowledge that Jesus is the only way of life and peace, Colossians 1:20.