It appears to me that it was the sin of Manasseh (Sacrificing children) where God finally had had enough and directed Babylon to conquer and enslave both Israel and Judah. If God had the patience through all of Israel's sinning, grumbling and worshiping idols made with hands, what do you think God is feeling about the United States and those countries that have legalized abortion and child slavery?
Remember Jesus' Words about children; Matt 18:2-5, 18:10, 18:14, 19:13-14...Mark 9:36-37, 10:13-16...Luke 9:47-48, 18:15-17...
And we aren't even into the rest of "man's inhumanity to man"...