Simple question, simple answer.
In the land of the free and the home of the brave, who are you and who's your slave.
Neither.
If you are a Christian, you body belongs to God, and was given to you to do his work in the world
However, we doctors are also obeying the Redeemer and Great Healer when we study for years and learn how to treat and care for the sick. In the words of the great healer (and Christian) Pare: "I treated him, but God healed him".