The House of the Lord
Rev 20:4-6 And I saw thrones, and they sat on them, and judgment was committed to them. Then I saw the souls of those who had been beheaded for their witness to Jesus and for the word of God, who had not worshiped the beast or his image, and had not received his mark on their foreheads or on their hands. And they lived and reigned with Christ for a thousand years. But the rest of the dead did not live again until the thousand years were finished. This is the first resurrection. Blessed and holy is he who has part in the first resurrection. Over such the second death has no power, but they shall be priests of God and of Christ, and shall reign with Him a thousand years.
At the establishment of the Millennium Rule of Christ, the 144,000 and the hundreds of thousands of the remnants Israeli Christians will be with our Lord Jesus in His house in Jerusalem. Since they will be with the Lord just like in heaven, there will be no marriages nor new birth then.
Our Jesus will have to build a huge temple on the tops of many mountains, (which will be flattened by the great earthquake) in order to house all of them.
Mic 4:1-2 Now it shall come to pass in the latter days that the mountain of the LORD's house shall be established on the top of the mountains, and shall be exalted above the hills; and peoples shall flow to it. Many nations shall come and say, "Come, and let us go up to the mountain of the LORD, to the house of the God of Jacob; He will teach us His ways, and we shall walk in His paths." For out of Zion the law shall go forth, and the word of the LORD from Jerusalem.
The Great Tribulation Martyrs
At the moment the population on earth < 8 billion, but after World War 3 with a quarter of mankind killed, the population should be < 6 billion. At Rapture the elect are taken back to heaven and half of those left behind will be killed during the 6th Seal. Thus, before the opening of the 7th Seal, the population will be about two and a half billion. At the 7th trumpet with more than 50% killed, there will only be about a billion people left on earth - all having the mark of the beast.
The Rapture will see millions or billions of elect (representing godly Christians over these 2,000 years) caught up to heaven during the 1st Resurrection.
To help rule just a few hundred thousands of Israeli Christians and a billion people, God needs only to choose the thousands of gloriously resurrected martyrs in the Great Tribulation (just like Gideon choosing only 300 soldiers).
No New Converts
Rev 20:7-9 Now when the thousand years have expired, Satan will be released from his prison and will go out to deceive the nations which are in the four corners of the earth, Gog and Magog, to gather them together to battle, whose number is as the sand of the sea. They went up on the breadth of the earth and surrounded the camp of the saints and the beloved city. And fire came down from God out of heaven and devoured them.
Since the whole world have taken the mark of the beast, their DNA would have changed and making them human hybrids (no longer the image of God) meant for damnation. After the thousand years, these human hybrids (descendants of those with the mark or '666') will follow Satan to fight the Lord and His saints in Jerusalem.
God will then annihilate all these human hybrids with fire from heaven, just as He annihilated them with water from heaven in the deluge during Noah's time.