I will pour out my Spirit on the people of Israel

Ezekiel 39:21-29
I will display my glory among the nations, and all the nations will see the punishment I inflict and the hand I lay on them. From that day forward the people of Israel will know that I am the Lord their God. And the nations will know that the people of Israel went into exile for their sin, because they were unfaithful to me. So I hid my face from them and handed them over to their enemies, and they all fell by the sword. I dealt with them according to their uncleanness and their offenses, and I hid my face from them.
When I have brought them back from the nations and have gathered them from the countries of their enemies,I will be proved holy through them in the sight of many nations.
I will gather them to their own land, not leaving any behind. I will no longer hide my face from them, for I will pour out my Spirit on the people of Israel, declares the Sovereign Lord.
The judgment of God is a terrible thing, and Ezekiel conjures it up in horrifying pictures. The fact that these chapters immediately precede Ezekiel's vision of the new Temple in which God dwells among his people, gives added point to John's choice of Gog and Magog to represent all who oppose God in the last great battle instigated by Satan at the end of time.
Why?
God is holy  and is sovereign Lord. God will let nations know his terrible punishment and why he hide his face from Israel, it is because of their sins. God dealt with them according to their uncleanness and their offenses.
God proved holy through his people in the sight of many nations. 
In the day, God will pour out his Spirit on the people of Israel.
God let us know our sins and regret and turn to Him. All of these action is the grace of the Lord.
How?
Confess our sins and turn to the Lord, let the Holy Spirit come on us. God is the Lord!