Paul, a slave of Christ Jesus, called to be an apostle and set apart for the gospel of God - Romans 1:1
Those who follow the teachings of Jesus Christ have often chosen to wear what others would consider as derogatory labels with pride, often because they indicate a teaching that was espoused by Jesus or the apostles after him. Apart from the aforementioned sheep, one of the other terms that is oft used in the epistles by Paul is slave or more literally "bond-servant."
Paul in using this phrase is presenting the picture that was rare in his day, but not unheard of. Slavery during this period included a group of people who came under bondage in an attempt to pay a debt that was owed. Once the debt was paid or forgiven, the slave or servant was allowed to resume his or her life as a free person. But, occasionally, something extraordinary would occur. On a rare occasion, the slave would choose to voluntarily give up his freedom and serve the rest of his days as a slave, usually because he found life under his master was much better than a life of freedom, due to the goodness of his master. Such a servant would be marked physically, sometimes with the piercing of an ear, to show that he was a voluntary slave.
Paul equates this situation with that of the Christian. Having found a God in whom he believes and believing that obedience to this God is better than a life of freedom, the Christian voluntarily gives up his freedom and pledges his life as a servant to this God, effectively saying that the fear of the LORD is the end of freedom. | 
