In wisdom literature 3+1, sometimes followed by 3+1, is a common pattern. The plus one gives the punch. Thus in Revelation the answer to the question “How long?” is 3.5 and not 4. Normally the plus one is a statement of utter judgment, thus it is +1/2 and not +1. But the structure of Revelation — both its rhetorical structure (7 cycles plus one) and its formal literary structure (3 visions plus one) — have a plus one that is not judgment but new heavens and earth. Why 3+1 and 7+1? Do the math. 3+1=4. 7+1=8, or better yet, (3+1)+(3+1)=8. But either way, 3+1 visions or 7+1 cycles, the plus one in Revelation is the same: the new heavens and earth. The very structure of the book is designed to highlight the good news.
The +1 (eighth) cycle begins with a threefold mention of the number seven: “Then came one of the seven angels who had the seven bowls full of the seven last plagues and spoke to me, saying, “Come, I will show you the Bride, the wife of the Lamb” (Rev 21:9). This is an introductory statement to the +1 (fourth) vision “in the Spirit” this time to “a great, high mountain” (Rev 21:10). John again sees the holy city (new) Jerusalem coming down out of heaven from God (Rev 21:10 – compare with Rev 21:2). In Rev 21:2 the city is described as “prepared as a bride adorned [with jewels, as we will see] for her husband” a point made in Rev 21:9. Now the city is described as “having the glory of God, its radiance like a most rare jewel, like a jasper, clear as crystal” (Rev 21:11). Like “crystal” is the description of the firmament of the sky and thus the “sea” before the throne (cf. Rev 4:6, 22:1, Ezekiel 1:22, 10:1, cf. Cycle One’s commentary). The idea is that the star-studded firmament is compared to the glory of God.
Number patterns continue in the next few verses. Rev 21:12 mentions twelve thrice. Rev 21:13 mentions three four times (3×4=12). And Rev 21:14 mentions twelve thrice. The city is 12,000 stadia — a multiple of 12 and 1000 (Rev 21:16). The wall is 144 cubits thick — 12×12 (Rev 21:17). And after listing twelve jewels (Rev 21:19-20) it mentions the number twelve two more times in Rev 21:21 and once in Rev 22:2. We have seen already that the number twelve signifies the people of God (being the number of tribes, etc.). The number twelve is mentioned 10 times in the cycle/vision (including Rev 21:16 in Greek but not the “twelfth” jewel). The streets are made of pure gold. This is the specs of that city having the glory of God and reflecting His radiance. Because of the symbolism of the number 12 the reader is not meant to distinguish the city from the people in it. The saints are prepared as the bride of Christ, they have the glory of God and reflect His radiance like jewels. The twelve jewels mentioned are meant to be associated with the jewels on Aaron’s breastpiece that also symbolized the glory-image-radiance of God. The idea is the saints are re-created in the image of God.
Now not only the sea is gone but also the night (as well as the sun and moon). The sun and moon luminaries were designed to reflect the heavenly realm and thus are symbolically called the heavens above but now the ‘real thing’ God Himself replaces the signs. This fulfills Isaiah 60:19-20. The gates will never need to be shut because there is no fear of attack in fulfillment of Isaiah 60:11, which also notes the wealth of the nations and their kings entering the city. This wealth would include possessions, gold, but also their talents and cultural and intellectual achievements. The passage builds on the tradition of describing the new creation with temple imagery and dimensions (cf. Ezekiel 48). Poythress notes that the shape is a cube, which is also the shape of the Most Holy Place — but this time magnified greatly. Thus there is no temple because the whole city is the Most Holy Place — God fills the whole. And the Lamb of God is the lamp showing the way for the nations and their kings to bring their glory into the city. Nothing dishonorable or unclean enters the city — no one who does detestable or false things enters the city — only those written the the Lamb’s book of life can enter. Indeed, the people are unable to sin.
The last five verses bring a number of the themes of Revelation together, the theme of testimony awaiting verse 6 which we discussed alongside the introduction. The river of the water of life flows down Mount Zion from the throne of God and of the Lamb. This is an Edenic description complete with the tree of life with twelve kinds of fruit yielding fruit every month of the year for twelve months and leaves for the healing of the nations (cf. Ezekiel 47:12). The people of God get to eat of the tree of life and to see the face of Jesus and His name, YHWH, will be on their foreheads (the unknown name of Rev 19:12, cf. Rev 9:4, 14:1). John then reiterates that there will be no more night nor need of the sun for the Lord God will be the light. And he adds about the saints, “they will reign forever and ever.” Thus we see that their reign was not limited to the millennium discussed last time.
All of these points are taught by a very symbolic vision of the new heavens and earth. The plus one of Revelation is indeed good news for them that believe in Jesus Christ for salvation.