We don't like to think about anyone owning us. We would rather focus on our freedom of choice and our ever-increasing desire for independence. Starting from when we are children, we want to say what we want to say, wear what we want to wear, go where we want to go and do what we want to do. We even convince ourselves that we have no master and that our self-ambition, personality, intelligence and abilities will bring success and happiness.
The truth is that we are all slaves in one way or another. We may believe that we are fully independent, but instead we are serving one of two masters.
In Romans 6, Paul presents the parallel paths. You are either a slave to sin which leads to death, or a slave to God which leads to righteousness. You might disagree with something so absolute and insist that you are a slave to nothing, but your verbal/mental denial doesn't change your status.
One type of slavery is true imprisonment-trapped in addictions, expectations, shameful sin and ignorance. One type of slavery is ironically one of the most freeing ways to live and brings hope, mercy, grace, goodness and love.
Unlike slavery in the physical world, we get to choose who will own us and in fact already have.