http://www.desiringgod.org/ResourceLibrary/Sermons/ByDate/2000/39_Slaves_to_God_Sanctification_Eternal_Life/
John Piper - Romans 6:20 Slaves To Sin or Slaves To God, Sanctification, Eternal Life

Romans 6:20-22

For when you were slaves of sin, you were free in regard to righteousness. 21 Therefore what benefit were you then deriving from the things of which you are now ashamed? For the outcome of those things is death. 22 But now having been freed from sin and enslaved to God, you derive your benefit, resulting in sanctification, and the outcome, eternal life.