Revelation 10:7 tells us that when the seventh trumpet sounds, “the mystery of God is finished” and that this is “good news.” The good news is “The kingdom of the world has become the kingdom of our Lord and of His Christ, and He will reign forever and ever” and “New Jerusalem, coming down out of heaven from God” (Rev. 11:15, 21:2).
The mystery was revealed to the apostles and presented by them to us (Eph. 3:3-4).
In the dispensations from Adam to Moses and from Moses to Christ, everything was unveiled, manifested, and there was no mystery. It will be the same in the dispensation of the millennial kingdom and in the new heaven and new earth — everything will be unveiled and there will be no more mystery. But in the dispensation from Christ to the millennial kingdom, everything is a mystery. The incarnation of Christ, as the beginning of this dispensation of mystery, is a mystery (1 Tim. 3:16). Christ Himself (Col. 2:2), the church (Eph. 3:4-6), the kingdom of the heavens (Matt. 13:11), the gospel (Eph. 6:19), the indwelling of Christ (Col. 1:26-27), and the coming resurrection and transfiguration of the saints as the end of this dispensation of mystery (1 Cor. 15:51-52) are all mysteries that were hidden in the times of the ages (Rom. 16:25; Eph. 3:5; Col. 1:26). All these mysteries will be completed, finished, and will be over at the trumpeting of the seventh trumpet.*
At present, New Jerusalem is a mystery. It is the product of all the forgoing New Testament mysteries. New Jerusalem is the outcome of Christ’s incarnation, His death (including the creation of the new man – Eph. 2:15), His resurrection (including our regeneration – 1 Peter 1:3), the perfecting of all the members of the Body for our ministry in building up the Body of Christ (Eph. 4:11-13), and the growth of His Body which is our building up in love (Eph. 4:15-16).
New Jerusalem is also the result of our redemption, reconciliation, renewing, sanctification, transformation, and more. These matters are mysterious because they are in the spiritual realm, not in the physical realm. Eventually, as Revelation 10:7 states, all these mysteries will be completed to open the door for the kingdom and New Jerusalem to appear to all men.