This is so true, it is the way of salvation. Now, a person is saved through repentance and asked Christ for forgiveness, sin has no effect on him now. It is as if he had never sinned. Paul asks if, once this happens and you are dead to sin, forbid he says, that you should choose to live in sin. Matthew said in 3;2 that the ministry of Christ consisted of "Repent for the kingdom of God is at hand". To repent is a matter of your choice of what you want to do about sin. We know it is only through Christ we are free of it, but our choice is up to us.