Ezekiel 37 tells us how Israel will be restored. God shows Ezekiel a valley full of dry bones and tells him that is the current condition of Israel and commands him to prophesy to the bones.
So I prophesied as I was commanded. And as I prophesied, there was a sound, and behold, a rattling, and the bones came together, bone to its bone. And I looked, and behold, there were sinews on them, and flesh had come upon them, and skin had covered them. But there was no breath in them.
Ezekiel 37:7,8 ESV
That represents the state of Israel today. They are a nation that is strong militarily and economically but they are still dead spiritually because they have not yet acknowledged Jesus as their Messiah.
Then he said to me, “Prophesy to the breath; prophesy, son of man, and say to the breath, Thus says the Lord God: Come from the four winds, O breath, and breathe on these slain, that they may live.” So I prophesied as he commanded me, and the breath came into them, and they lived and stood on their feet, an exceedingly great army.
Ezekiel 37:9,10 ESV
This will take place when Jesus returns, so in a sense those who believe the Messiah must return for Israel to be fully established are right. The present nation is merely the foundation for this to take place.