For most Christians the return of Jesus and the ushering in of God's Kingdom are central to their faith. And certainly there has been a high level of expectation that the time of Jesus' coming must be near.
The Unification Church propounds what for many Christians is an unacceptable proposition-that Jesus himself cannot return again to this earth. Jesus is a spirit, living in the highest realms of Paradise, surrounded by the spirits of devout departed Christians. The body in which his disciples witnessed his resurrection was in fact his spiritual body. In that sense Jesus is no different than any of us. Once we go to the spiritual realm that becomes our home for all eternity. Yes, it is possible that spirits can appear and give occasional guidance to people living on Earth, just as Jesus has done over the past 2000 years.
In this respect, it's important to understand that the Messiah cannot come on the clouds of heaven. While the verses implying the Lord will come riding triumphantly on clouds into this world are popular among Christians, it has to be admitted that there is the possibility that the clouds have a symbolic meaning.
The Unification Church teaching is that in order to redeem the original sin the Messiah must be born again on earth. Please consider Revelation 12:5. It talks of a child who is born of a woman, who will be caught up to the throne of God, and who will rule all nations with a rod of iron. Although some take this child to be symbolic of the church, the one who rules the world with a rod of iron (the truth) is clearly the Messiah. If one is willing to put aside the concept that the Messiah must come on the clouds, this verse implies strongly that the Messiah will be born as a child. Further, both Revelation 2:17 and 17:12 point to the Messiah coming with a new name, a name that only he himself will know.
Yes, the coming of the Lord will be like lightning that all will see (Luke 17:24), but first the returning Lord may have to suffer many things and be rejected (Luke 17:25). Why would the Christ suffer when he returns? It could only happen if he wasn't recognized, at least initially. If the Messiah comes on the clouds that is very unlikely.