Jeremiah Chapter 50 KJV verse three and four

"For out of the north there cometh up a nation against her, which shall make her land desolate, and none shall dwell therein, they shall remove, they shall depart, both man and beast"
Departing from Babylon is God's goal, one way or another. Do it voluntarily or be forced out for complete destruction is promised, in fact, the same thing they did to Israel has now come upon them, only worse. This is a fulfillment of Genesis 12:3. God's goal is that, when he's finished judging her, no one, man or beast, will inhabit Babylon because of a truth Babylon has become a "habitation of devils and the hold of every foul spirit and a cage of every unclean and hateful bird" Rev:18:2. The reference to devils obviously represents fallen angels that united with Satan in rebellion against God, the foul spirit's mentioned are referring to every human spirit that is not cleansed by the Blood of Jesus and the Holy Spirit's presence within and birds in scripture are often symbolic of the saints of God, or God's people and he is referring here to saints that choose to remain in Babylon after God has offered them freedom by his Spirit. They become unclean before God (they touch the unclean thing) and they become hateful, full of hate, unable to truly love, loving with lips only and not hearts. And notice they are caged. Saints who dwell in Babylon have no spiritual freedom whatsoever. The only place of true spiritual freedom on earth is "where the Spirit of the Lord is". "And then shall many be offended and shall betray one another, and shall hate one another"Mt:24:10. The hearts that belong to Satan, those dwelling in Babylon, are even now being exposed. They are easily offended, they betray their very own brothers and sisters in Christ, they hate others instead of loving them and they are quick to judge others but can not receive correction themselves. Hearts that belong to God are also being exposed at this time for "they loved not their lives unto death"Rev:12:11, "of whom the world is not worthy"Heb:11:38
Verse four - "In those days and in that time, saith the Lord, the children of Israel shall come, they and the children of Judah, TOGETHER, going and weeping: they shall go and seek the Lord their God".
This is for all who would be delivered from Babylon - true, heart broken repentance, for true heart felt repentance will produce tears, weeping, and a clear result of deliverance from Babylon is that God's children, his people, come together in unity. At Babel, they were seperated, and ever since, wherever that spirit of Babel is, there is seperation, division. When we see any group of Christians coming together in love for one another (careful though, the anti-christ will be able to unite the false christians too, except it won't be in love or in obedience to God), when we see them identifying themselves more with Christ than they do their own church or denomination, then we'll know Babylon is broken in them, when V 5 - "They shall ask the way to Zion with their face thitherward, saying, come let us join ourselves TO THE LORD IN A PERPETUAL COVENANT THAT SHALL NOT BE FORGOTTEN".