Then they shall know that I am the LORD their God, because I sent them into exile among the nations and then assembled them into their own land. I will leave none of them remaining among the nations anymore. And I will not hide my face anymore from them, when I pour out my Spirit upon the house of Israel, declares the Lord GOD.
The future that God declares for the Jewish people is that they will assemble from among all the nations in which they are scattered and return to the land of Promise. He will sovereignly intervene to assemble them. No Jew will remain outside the borders of Israel in that day.
Once again, in the reconstituted nation, the power of The Lord will be displayed in Israel. God was "hiding His face" in the scattering of the exile. But in the reassembled nation, His power and presence would be clearly known. Once again God's Spirit would be poured out upon the nation. And the world would know that He is God.
God's people exist to display the power of His presence and person. This was God's purpose for Israel. It is God's purpose even today. This specific set of promises applies exclusively to a future time for ethnic Israel. But the principle of God displaying Himself as His Spirit controls His people applies to all people whom He calls to Himself. God's Spirit resides within Christians. Are we making Him known in our world?