God revealed to the Old Testament Prophets that in His timing He would make the Mystery clear and when the Seventh Trumpet sounds, the Mystery of God will be finished.
Because then the Mystery of Iniquity would be revealed, in whom Satan will dwell after he is cast out of Heaven and in his destruction, and the binding of Satan, and the setting up of the Millennial Kingdom of Christ, shall the promises be fulfilled to the Prophets, that peace and righteousness will reign on the earth.