Isaiah 40:3-5
A voice is calling, "Clear the way for the Lord in the wilderness; make smooth in the desert a highway for our God. Let every valley be lifted up, and every mountain and hill be made low; and let the rough ground become a plain, and the rugged terrain a broad valley; --
God sent John the Baptist to prepare the way for Jesus and he quoted these verses, saying, in effect, that the mountains and valleys were in our hearts; that our pride and our discouragement must be dealt with to prepare our hearts to receive Jesus.
And the Book of Revelation tells us that the actual mountains and valleys on this Earth will be leveled by earthquakes and other cataclysmic events immediately preceding the coming of the Lord.
then the glory of the Lord will be revealed, and all flesh will see it together; for the mouth of the Lord has spoken."
Then when Jesus appears, coming down through the clouds, is when all flesh will see it together, at the same time. The Church will be raptured while He is still in the clouds, and we will return with Him, in our Resurrection bodies, as His feet touch the Mount of Olives (Zechariah 14:4) and He wages and wins the Battle of Armageddon.
And the Jews all over the world will also see Him whom they have pierced, and realize that He really is their Messiah, and be saved. And since they weren't Resurrected with the Church, and they weren't fighting against Him in the Battle of Armageddon, then they will be the ones who enter into His 1000-year Kingdom in their human bodies. Since they already live all over the world, they will repopulate the world over that 1000 years.
Even so, come, Lord Jesus!
