During the sanctifying of the earth, the New Jerusalem and the Old Jerusalem will both be caught up and preserved. Then both of these great cities of God will return, the New Jerusalem coming first and then the Old Jerusalem. This fulfills Christ's prophecy that the Jews who were the first to receive the gospel will be last to come back to the glorified earth and the house of Joseph which received the gospel after the Jews will be the first to return in the New Jerusalem when the earth is glorified.