As explained above, all religions, which have sought the same ultimate purpose, are gradually coalescing into one cultural sphere based on Christian ideals (cf. Eschatology 4.2).
Christianity does not exist for its own sake, but has as its final mission the fulfillment of the purposes of all the religions in human history. Christ at the Second Advent, who is to come as the center of Christianity, is the person of the Maitreya Buddha who is to return according to the teachings of Buddhism, the True Man who is awaited in the Chinese religious tradition, and the Chongdoryong for whom many Koreans yearn. He is the central figure whose advent is expected in other religions as well.
Consequently,at the Second Coming of Christ, all spirits who believed in religions other than Christianity during their lifetime will, like the spirits in Paradise, also return to earth to be resurrected, even though the timing of their return will vary depending upon their spiritual position.
These spirits must guide the earthly believers of their respective religions to Christ at the Second Advent and assist them to believe in him and attend him in his work to fulfill God’s Will.
We can find a parallel example of this at the First Advent: the three wise men from the East, who were Zoroastrians, came in search of Jesus and worshipped him at his birth (Matt. 2:1-12). Accordingly, all religions will eventually be united around a revived Christianity.
Sun Myung Moon