Revelation 21:4 Tells us the first things (old order of things/former things) have passed away. This is clearly speaking of the end of the old covenant. In Revelation 21:1-7 we see that The dwelling place of God is with man. He will dwell with them, and they will be his people. So, again, this about the new covenant relationship with God's people, not a literal city or building. Nor is it about heaven, as some people think.
The church no longer needs a temple because Christ brings the presence of God to his people. Christ replaced the temple (Revelation 21:22). This is theologically significant because no longer could anyone claim that salvation was in the temple rituals. Salvation rests only in Christ.
The New Jerusalem is the bride (Revelation 21:2), which means the bride of Christ (Matthew 22:1-14; John 3:29; 2 Corinthians 11:2; Ephesians 5:22-32; Revelation 19:7-8). The picture that is painted for us by John is that Israel was a harlot (Revelation 17:1, 5, 15; 19:2). Israel was the original bride of the LORD (Jeremiah 2:1). But, throughout the Bible, whenever Israel is unfaithful, she is characterized as a "harlot" and an "adulterer." See: Deuteronomy 31:16-18; Isaiah 1:21; Jeremiah 2:20; 3:6-9; Ezekiel 16:15, 26, 28; Hosea 9:1.For her marital unfaithfulness, she received divorce and punishment. Then we see the new bride-the church (The Kingdom), coming to take her place. Old Covenant Jerusalem is destroyed and replaced by the New Jerusalem of which first-century Christians were citizens.