Hey there, Laura … Here’s my take on the Millennium.
The "Lord's Day" (the Millennium) is one day in God's time, but 1000 years in ours.
But, beloved, be not ignorant of this one thing, that one day is with the Lord as a thousand years, and a thousand years as one day. 2 Peter 3:8
Then I saw an angel coming down from heaven, having the key to the bottomless pit and a great chain in his hand. He laid hold of the dragon, that serpent of old, who is the Devil and Satan, and bound him for a thousand years; and he cast him into the bottomless pit, and shut him up, and set a seal on him, so that he should deceive the nations no more till the thousand years were finished. But after these things he must be released for a little while. - Revelation 20:1-3
During the Millennium, everyone who has ever lived on the earth during the flesh age will be present (except Satan, of course).
Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years. Revelation 20:6
The 1st Resurrection will take place in the beginning of the Millennium. This First Resurrection is for all of the overcomers—the Christians who endured until the end (the Elect).
And ye shall be hated of all men for my name's sake: but he that shall endure unto the end, the same shall be saved. Mark 13:13
And many false prophets shall rise, and shall deceive many. Matthew 24:11 And because iniquity shall abound, the love of many shall wax cold. Matthew 24:12 But he that shall endure unto the end, the same shall be saved. Matthew 24:13Blessed and holy is he that hath part in the first resurrection: on such the second death hath no power, but they shall be priests of God and of Christ, and shall reign with him a thousand years. Revelation 20:6
During the 1000 years, the Zadok (overcomers) will teach the dead (those who did not overcome) the difference between what is Holy and what is profane. Those who did not make the "cut" during the first resurrection will have to wait a thousand years for the second resurrection, the great white throne judgment, to receive eternal life, which is what "to live again" means.
The functions of the priesthood, as well as those of ruling and judging, will be assigned to God's elect (overcomers)! During the Millennium, they will be the "ruling class."
Rev. 20:7 And when the thousand years are expired, Satan shall be loosed out of his prison,
[8] And shall go out to deceive the nations which are in the four quarters of the earth, Gog and Magog, to gather them together to battle: the number of whom is as the sand of the sea.
Those who follow the Lord after Satan's release will be granted eternal life at the end of the "Millennium" This is the 2nd. resurrection.
And I saw a great white throne, and him that sat on it, from whose face the earth and the heaven fled away; and there was found no place for them. Revelation 20:11 And I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works. Revelation 20:12 And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works. Revelation 20:13 And death and hell were cast into the lake of fire. This is the second death. Revelation 20:14 And whosoever was not found written in the book of life was cast into the lake of fire. Revelation 20:15