The word, slave, is a strong word. In fact, it is so strong that we don't even use it today when we refer to the global problem of human trafficking. We use the term "human trafficking," but the reality is that people's freedom is stolen from them and they are forced to be slaves. They are controlled both through emotional and physical threats. This is such a deplorable thing to do to another human and for most people it is considered unacceptable. But at the time the book of Romans was written, slavery was considered acceptable by many. So, when the reference to slavery was used, the audience reading it would understand how the life of a slave was not their own. Please use the link and read how it was used to make a point about who we are through Christ: Romans 8:12-17.
I love the difference that is made in these verses! I want you to keep the picture in your head of what a slave truly is. This is a person who is being forced to do something they do not want to do with little or nothing in return. When we choose to follow our human nature, we are told that we become slaves to our sin. There is no way out accept through Christ. When we allow ourselves to be controlled by the Holy Spirit, we are not under his control as slaves. We are brought into His family as His children. What difference! We are given great promises as His children.
What God wants from us isn't always easy, but we are given His power through the Holy Spirit to get it done. We are not slaves to sin; we are children of our Creator. The Holy Spirit doesn't make us obey as a fearful slave; instead we obey out of love. We obey out of confidence that we are God's children!
Do you believe that in Christ you have freedom?