Paradox lies at the heart Christian faith. Strength is found in weakness, the first will be last and losing life is how we find it. Most striking, we find the mighty God in a crib and on a cross. The majesty of the Creator is his humility.
Peter touches another paradox in his first letter. He states, “Live as people who are free, not using your freedom as a cover-up for what is evil, but living as servants of God” (1 Pet 2:16). You are free, the gospel has done that for you. But people freed by the gospel are strange. They use their freedom to ensure their slavery.
The word servants (δοῦλοι) literally means “slaves.” The gospel liberates us for joyful service to others. Martin Luther’s book, The Freedom of the Christian builds on this paradox. His preface says it well.
A Christian is a perfectly free lord of all, subject to none.
A Christian is a perfectly dutiful servant of all, subject to all.
These two theses seem to contradict each other. If, however, they should be found to fit together they would serve our purpose beautifully. Both are Paul’s own statements, who says in I Cor. 9:19, “For though I am free item all men, I have made myself a slave to all,” and in Rom. 13:8, “Owe no one anything, except to love one another.” Love by its very nature is ready to serve and be subject to him who is loved. So Christ, although he was Lord of all, was “born of woman, born under the law” [Gal. 4:4], and therefore was at the same time a free man and a servant, “in the form of God” and “of a servant” [Phil. 2:6–7].
Another great treatment on this theme is a book by Murray J. Harris called Slave of Christ: A New Testament Metaphor for Total Devotion to Christ. We are freed for slavery.