Battle of Gog and Magog at End of Millennium

Revelation 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.

9 And they went up on the breadth of the earth, and compassed the camp of the saints about, and the beloved city: and fire came down from God out of heaven, and devoured them.

10 And the devil that deceived them was cast into the lake of fire and brimstone, where the beast and the false prophet are, and shall be tormented day and night for ever and ever.

Joseph Smith

The battle of Gog and Magog will be after the millennium. The remnant of all the nations that fight against Jerusalem were commanded to go up to Jerusalem to worship in the millennium. (Teachings of the Prophet Joseph Smith, p.280)

Bruce R. McConkie

"And again, verily, verily, I say unto you," saith the Lord, "that when the thousand years are ended, and men again begin to deny their God, then will I spare the earth but for a little season." The language here bears out the concept that apostasy and its consequent evil way of life will be the key that opens the prison in which Satan is bound. (The Millennial Messiah, p.695-696)

Joseph Fielding Smith

Will the earth go back to the telestial order after the millennium? No, but the people on the face of the earth, many of them, will be like the Nephites who lived 200 years after the coming of Christ. They will rebel against the Lord knowingly, and the great last struggle will come, and the devil and his forces will be defeated; then the earth will die and receive its resurrection and become a celestial body. The resurrection of the wicked will take place as one of the last events before the earth dies. (Doctrines of Salvation, 1:87)

Satan will be loosed to gather his forces after the millennium. The people who will be tempted, will be people living on this earth, and they will have every opportunity to accept the gospel or reject it. Satan will have nothing to do whatever with little children, or grown people who have received their resurrection and entered into the celestial kingdom.

Satan cannot tempt little children in this life, nor in the spirit world, nor after their resurrection. Little children who die before reaching the years of accountability will not be tempted; those born during the millennium, when Satan is bound and cannot tempt them, "shall grow up without sin unto salvation." (Doctrines of Salvation, 2:56-57)