Revelation 21:1-7
(Rev 21:1 KJV)
And I saw a new heaven and a new earth: for the first heaven and the first earth were passed away; and there was no more sea.

Here John begins a new vision and it is now that of the New Heaven and the New Earth which will be the eternal abode of the true believers. The verse tells us that the first earth and heaven has passed away because they were sin cursed and they were the home of Satan, the beast, and the false prophet. The New earth has no sea. The seas were a definite remnant of the flood of Noah and here we see there is no sea which means that there is no more reminders of judgment in the new earth since it is going to be a place of total righteousness because all the evil has been burned up.
(2 Pet 3:10 KJV) But the day of the Lord will come as a thief in the night; in the which the heavens shall pass away with a great noise, and the elements shall melt with fervent heat, the earth also and the works that are therein shall be burned up. All evil and its remnants has gone the way of the flame as the universe is purged of evil.

(Rev 21:2 KJV)
And I John saw the holy city, new Jerusalem, coming down from God out of heaven, prepared as a bride adorned for her husband.

Here John sees the new Jerusalem descending out of heaven. This new Jerusalem is the body of believers in their entirety. They are spoken of as a city and we can be sure of this because it is called a bride adorned for her husband and the body of Christ is the bride of Christ.

(Heb 11:10 KJV) For he looked for a city which hath foundations, whose builder and maker is God.

(Heb 12:22 KJV) But ye are come unto mount Sion, and unto the city of the living God, the heavenly Jerusalem, and to an innumerable company of angels,

(Heb 13:14 KJV) For here have we no continuing city, but we seek one to come.

These three verses all show us that when we become saved, we are part of that city of the living God and it is a continuing city, plus it is the city which God built. That means salvation was all of Him and we had nothing to do with it. Back In Galatians 4:26, the heavenly Jerusalem was already mentioned as the mother of us all. It is the new Jerusalem which gives spiritual birth to the believer.
(Gal 4:26 KJV) But Jerusalem which is above is free, which is the mother of us all. The name “Jerusalem” means “possession of peace.” Whenever God speaks of the body of believers, He speaks of them in the context of peace. That is, we have peace with God for eternity because when we became saved the war between us and God was over. (Rom 5:1 KJV) Therefore being justified by faith, we have peace with God through our Lord Jesus Christ:

(Rev 21:3 KJV)
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.

Here we read in this verse that God is now dwelling among His people for eternity. No longer is there any type of separation between God and His people. This dwelling among them is now a permanent thing. John heard a great voice out of heaven which is building upon verse 2 which calls the body of believers a holy city and here we have a further explanation of who that city is, it is the people of God. This verse is rooted in a verse back in Leviticus.
(Lev 26:11-12 KJV) And I will set my tabernacle among you: and my soul shall not abhor you. {12} And I will walk among you, and will be your God, and ye shall be my people. In Leviticus, God had already written that He would tabernacle among the people of Israel but in Rev. 21:3, we have the ultimate fulfillment of that promise which is for eternity.

(Rev 21:4 KJV)
And 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.

One of the great characteristics of the new heaven and earth, is that there will be nothing which will cause any sorrow anymore.
(Psa 16:11 KJV) Thou wilt show me the path of life: in thy presence is fulness of joy; at thy right hand there are pleasures for evermore. All of the suffering and the trials which the believers had suffered in the old order has now been eternally abolished. Things like sorrow, tears, pain, and death are all part of the former life and are passed away forever. (1 Cor 15:54 KJV) So when this corruptible shall have put on incorruption, and this mortal shall have put on immortality, then shall be brought to pass the saying that is written, Death is swallowed up in victory. What a glorious future for the believer!

(Rev 21:5 KJV)
And he that sat upon the throne said, Behold, I make all things new. And he said unto me, Write: for these words are true and faithful.

Here is God declaring that He is going to make all things new. The very Creator of the first earth and universe is now going to recreate it in total righteousness and purity. He commands John to write these words because they are true and faithful, which means that it will come to pass. In fact, if God spoke it, it is as good as if it had been completed already.
(Titus 1:2 KJV) In hope of eternal life, which God, that cannot lie, promised before the world began;

(Rev 21:6 KJV)
And he said unto me, It is done. I am Alpha and Omega, the beginning and the end. I will give unto him that is athirst of the fountain of the water of life freely.

When the Lord Jesus Christ was on the cross, He said “It is finished.” The final sacrifice for sin had now taken place and the only thing left was for the church to go out and evangelize the world and bring in all God’s Elect. Here God states concerning the New Heaven and New Earth, that “It is done.” Just as the Son completed God’s salvation plan, God Himself has completed the recreating of the New Heaven and New Earth. God is called, the Alpha and Omega, which are the beginning and ending letters of the Greek Alphabet. By using these terms, God is telling us that all things begin with Him and all things have their completion (end) in Him. Then a great promise is made that those who thirst will be given the water of life freely.
(Mat 5:6 KJV) Blessed are they which do hunger and thirst after righteousness: for they shall be filled. The only ones who will thirst after righteousness are those whom the Lord named from the foundation of the world as they will be the only ones who will be spiritually qualified to hear and understand the true Gospel and with that understanding will come salvation. This is not an academic understanding but a spiritual understanding.

(Rev 21:7 KJV)
He that overcometh shall inherit all things; and I will be his God, and he shall be my son.

The one who overcomes is the true believer. We have seen this word used in all of the letters to the seven churches that those who overcome will have promises of eternal life. We overcome through the blood of the Lord Jesus Christ. God promises that those who become saved will be children of God, as He will be their God and they shall be His son.
(Rom 8:37 KJV) Nay, in all these things we are more than conquerors through him that loved us. The words “more than conquerors” is the same word used for “overcometh.” Through the blood of Christ, we are not only called conquerors but called more than conquerors.