We are all slaves.
The Hebrews had made themselves slaves to the worthless gods of the Egyptians, so God made them slaves to Pharaoh.
God did not bring the people out of Egypt so they could be an autonomous, self-mastered people. He spoke to Pharaoh through Moses, “Let my people go, that they may serve me in the wilderness.” It’s not to cast off slavery, it’s to be slave to the right master.
“No one can serve two masters, for either he will hate the one and love the other, or he will be devoted to the one and despise the other. You cannot serve God and money.”
So, who are we going to serve? If we serve ourselves, or chase money, or strive for influence to leverage ourselves in the world, seeking to fill our desires with so many false gods, then we are slaves to sin. This is true slavery. If we take up the cross and put to death the desires of the flesh that war against the Spirit, if we love God and love our neighbor – that is, if we serve them – we are slaves to righteousness. This is true freedom.
This is why when Jesus put on human flesh to become like one of us, he took on the form of a servant. He told His disciples, “the Son of Man came not to be served but to serve,” and, “whoever would be first among you must be slave of all.”
He came to set us free so that we might be slaves.