Devotional from John Piper: The Best form of slavery.
1 Peter 2:16 (NIV)
16 Live as free people, but do not use your freedom as a cover-up for evil; live as God’s slaves.
Colossians 3:24 (NIV)
24 since you know that you will receive an inheritance from the Lord as a reward. It is the Lord Christ you are serving.
Ephesians 6:6 (NIV)
6 Obey them not only to win their favor when their eye is on you, but as slaves of Christ, doing the will of God from your heart.