The work of the redeeming Christ in His overcoming death and life-supplying resurrection is signified by the element of the pearls of the gates (Rev. 21:21a). The pearls signify the regenerated believers produced by Christ's death and resurrection. Pearls are produced by oysters in the waters of death. When an oyster is wounded by a grain of sand, it secretes its life-juice around the grain of sand and makes it into a precious pearl. This depicts Christ as the living One coming into the death waters, being wounded by us, and secreting His life over us to make us into precious pearls for the building of God's eternal expression.
The twelve gates of the city are twelve pearls, signifying that regeneration through the death-overcoming and life-secreting Christ is the entrance into the city. This also indicates that Christ's death plus His resurrection will produce us to be the very entrance for people to come into the holy city. Today in the local churches there are some brothers who are like gates, through which people can enter into the realities of the holy city.
Paul said that we should build the church today with gold, silver, and precious stones (1 Cor. 3:12a). In the New Jerusalem there will be gold and precious stones but no silver. Silver is in the church today, but it will be replaced by pearl in the New Jerusalem. In 1 Corinthians 3 we have silver because in typology silver represents redemption. Redemption deals with sin. For eternity in the New Jerusalem sin will be banished and eliminated. Therefore, in eternity there will be no need for redemption, for silver. The need there is not for silver, for redemption, but for pearl, for regeneration. Redemption is to take away sin; regeneration is to bring in the divine life.
The composition and constitution of the New Jerusalem is absolutely of the consummated Spirit in His transformation work, signified by the essence of the precious stones of the wall and its foundations (Rev. 21:11, 18a, 19-20). These precious stones signify the transformed believers (1 Pet. 2:5a) renewed by the Spirit's transforming work (Titus 3:5; Rom. 12:2a).
The New Jerusalem is purely of God the Father, exclusively of Christ, absolutely of the Spirit, and with the regenerated, transformed, and glorified human beings (Rev. 21:12b, 14b). We have been regenerated, we are on the way of transformation, and we will reach the goal of glorification. The Triune God will be fully mingled with us as transformed and glorified persons.