But you did not listen to me

Jeremiah 25:1-1 Coming invasion
Jeremiah the prophet said to all the people of Judah and to all those living in Jerusalem: 
But you did not listen to me,” declares the Lord, “and you have aroused my anger with what your hands have made, and you have brought harm to yourselves.”
I will summon all the peoples of the north and my servant Nebuchadnezzar king of Babylon,” declares the Lord, “and I will bring them against this land and its inhabitants and against all the surrounding nations. I will completely destroy them and make them an object of horror and scorn, and an everlasting ruin.
This whole country will become a desolate wasteland, and these nations will serve the king of Babylon seventy years.
The year is 605, when Nebuchadnezzar of Babylon routed the Egyptians at Carchemish. For 23 years Jeremiah has been repeating God's message, and still the people remain unmoved. Now he tells them that the city will fall and they will serve the Babylonians for 70 years in exile.
The judgment of God will also fall on the pagan nations who so richly deserve it and on Babylon itself.
Why?
But you did not listen to me so the judgment and destruction came to people of Judah.
Even the enemy could be God's servant to serve the Lord and let God's people be trained and turn to the Lord.
God is full of mercy, even he destroy the people  of Judah, but there is time limit, 70 years. His people will return to their home land.
How?
Obey God's word and be aware there is only the Lord I have to fear and worship. God is my hope and my salvation.