The angel takes John to the most important place of the city, which is the throne of God and of the Lamb. They are depicted as a shared fountain, which is the source of life for the inhabitants of the city. The water of life could be a reference to the Holy Spirit or it could be a reference to what the Holy Spirit brings to the city. This river reaches all the inhabitants – there is only one street on which they all live and the river keeps flowing, bringing the riches of God’s grace to all of his people.
John has already been told about the street in 21:21 where he was told it was made of gold. One assumes that the street is as long and as wide as the city. This would mean gold everywhere, which is a way of saying that the church will be ablaze with glory. What is rare here – gold – is used to depict how wonderful and great the life of the church will be there.
The street of the city contains a very large tree which extends over the river and covers each side of the street along its length, which means that it will be accessible to all the inhabitants of the city simultaneously. It looks as if the tree is likened to a shade, a reminder that the church then will be a place where all is comfortable.
Moreover, this tree of life bears fruit continually, on which the inhabitants can feed. There is nothing wasteful about this tree – even its leaves ensure healing. Leaves were a kind of medicine in the ancient world. I don’t think John is suggesting that any of the inhabitants can become ill; instead, he is saying that as long as they use the tree of life they will be healthy, which is what they will delight to do.
I suspect that access to the tree of life is a reminder of the fullness of eternal life. In Eden, Adam and Eve were barred from eating of the tree of life because it would have meant for them an eternal existence without hope. In contrast, because God’s people will have been restored to glory, it will be safe to have eternal life
Then John describes the activities of the members of the church now that the curse has gone. They shall be before the throne and engage in constant worship of God through the Lamb. Their worship in this life did involve access to the throne and adoration of its divine occupants. Yet it was often done as if they were in the night, unable to understand fully what they were doing and what God was revealing. In the eternal world, the members of the church will have full access to God through the Lamb. The light they will have will be direct, unlike light through a creation of God (the sun) or through what they made themselves (a lamp).
Unlike what happened to Adam in the original temple in Eden, the members of the church of Christ will never lose their royal status and they will reign for ever and ever. Throughout eternity to come, they will be the royal priesthood serving God through the leadership of their Mediator, their Prophet, Priest and King.