To me that means I'm going to sin, willfully or unwillfully, but God's grace is sufficient to cover my sin. My salvation lies in the act of recognizing God's grace in the act of sending Jesus to be our Christ.
I'll second that.
If I were to really accept God's grace, really perceive the depth of his love for us and truly understand what he has done for me, I don't think I could bear to sin against him. At the times when I am closer to God and more aware of Him, I am better. At the times when I drift away, I am worse.
The point I am making is that, for a Christian who has accepted Jesus and been "set free from sin", sin is not a thing of the past; it is a symptom of drifting away from Jesus, and acting right is a symptom of coming close to him. It's easy to get the cause and effect the wrong way around and conclude that God loves us in proportion to our righteousness; but in reality we begin to act the right way, to really abandon sin, when we begin to really understand his love and acceptance. His love is unconditional, and gradually it heals us.
The confusion is as old as Christianity and there are some great bits in Paul's letters about it. In 2000 years we still have not fully grasped the reality that God accepts us as we are
and works from there.