Revelation 21

After John had witnessed the opening and closing of the seven seals, and what seems the conclusion of judgement day, even the the fulfilling of the book -

"...in the right hand of him that sat on the throne a book written within and on the backside, sealed with seven seals." (New Testament | Revelation 5:1)

Or in other words, the fulfillment of the plan of salvation, John was privileged to see -

"...a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.
2 And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband.
3 And I heard a great voice out of heaven saying, Behold, the tabernacle of God is with men, and he will dwell with them, and they shall be his people, and God himself shall be with them, and be their God." (New Testament | Revelation 21:1 - 3)

Joseph Smith wrote that we believe as John wrote -

"...that Christ will reign personally upon the earth; and, that the earth will be renewed and receive its paradisiacal glory." (Pearl of Great Price | Articles of Faith 1:10)

In fulfillment, the earth and its people would be in a celestial state where -

"...God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away.
5 And he that sat upon the throne said, Behold, I make all things new." (New Testament | Revelation 21:4 - 5)

Again, I emphasize that this is the conditions and state of those that are righteous for -

"He that overcometh shall inherit all things; and I will be his God, and he shall be my son." (New Testament | Revelation 21:7)

Those that confess Christ but do not repent or -

"...the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death." (New Testament | Revelation 21:8)

The second death would be those not allowed to "inherit all things" and live in this "new earth".

John proceeds to attempt to describe in earthly words the glorious nature of the new earth and the individuals that would be allowed therein with the warning that -

"...there shall in no wise enter into it any thing that defileth, neither whatsoever worketh abomination, or maketh a lie: but they which are written in the Lamb's book of life." (New Testament | Revelation 21:27)

It is those, the righteous, that are written in "the Lamb's book of life" that will be His sons and daughters.