The Tower of Babel
In the Tower of Babel, it looks benign; those people working together to build a tower - what's wrong with that? Why would God be jealous of the progress of mankind? But it was a slavery that was building again.
God was actually freeing the people from slavery when He broke up this empire – the tower of Babel. In an aspect, the tower Babel was not just a form of slavery, but was also demonic. In the sense that they offered human sacrifice, particularly sacrificing children.