Here in Revelation 22:1-2 we need to understand that John is being given a description of the entire ONE Eternal Kingdom (seen and unseen realms) of God at work. In Revelation 22, John is able to see the heavenly unseen source of the River and Tree of Life (the very throne of God). This full access and perfected blessing is available to all believers who have left this world (seen realm) and now live forever in His presence in this heavenly unseen Kingdom realm.
We also see the source and activity in the seen realm with the “leaves of the Tree of Life” which are for the healing of the nations. The church on earth is the seen realm of this one Eternal Kingdom. There is no “healing” that needs to be done in heaven –> this is clearly saying that life continues on earth after the creation of the “new heavens and earth,” and unbelievers are still continuing to exist on earth and need “healing” (salvation). The “leaves” are the Words of Christ which He said “will never pass away” (Matt. 24:35) –> the “everlasting gospel” spoken of in Revelation 14:6 –> which the church is to forever preach to “every nation, tribe, tongue, and people –> which brings salvation and healing. The Holy Spirit is the “River of Life” Who works among His church on earth to bring this salvation and healing to the nations. Together the heavenly unseen realm and the earthly seen realm (church) make up this one Eternal Kingdom.
John’s heavenly vision in Revelation 22:1-2 of the unseen heavenly realm of the Kingdom is quoted from, and synchronous with, Ezekiel’s vision of the seen earthly realm of the Kingdom in Ezekiel 47. In Revelation, John describes fruit trees lining the river on both sides, with leaves which bring healing to the nations, or Gentiles. In both accounts the river comes from God’s throne, it is lined with trees bearing fruit, and the leaves of the trees produce healing (Ezek. 47:12; Rev. 22:2). This parallel picture of both realms is one of the life-giving Spirit flowing from God (unseen heavenly realm) through His people (the church) on earth (seen realm) into the heathen nations to produce renewal, spiritual food and healing.
Ezekiel 47 with its description of the new temple (the church) that was built in the Last Days, with its little trickle of water coming out of the temple threshold, is an invaluable illustration of this idea of the river of life always growing and spreading in the world to change every culture, but never reaching perfection. Ezekiel 47:11 shows us that there will always be some stagnant back-waters where the living water will not reach. There will always be nations and cultures which resist the gospel and remain in darkness. But we take the light to them anyway, regardless of whether they choose to walk in that light or not. We have the promise of the Lord that “of the increase of His government and peace there will be no end…from that time forward, even forever.” (Isa. 9:7), and that it will always be available to all generations forever and ever (Eph. 3:21).
Jesus prayed in Matthew 6 that the Father’s Kingdom would come and His will be done ON EARTH (seen realm) as it is already being done IN HEAVEN (unseen realm). The Kingdom will continue growing and spreading throughout the SEEN realm on earth, but it will never reach perfection here on earth (seen realm). Perfection is only found in heaven (unseen realm). The earth is where the visible church has its activity. The Cross and the Parousia were two world-changing events, which forever and irreversibly affected both the seen and unseen realms.
See also related “Topic Studies & Terms”:
“River of Water of Life (Revelation 22:1)”
“Heavens and Earth (Prophecy)”
Related full “Study Series” (available upon request if not hyperlinked):
[For a more in-depth study see eschatology “Study Series 16 Lesson 10 Rev. Chapter 22”]