The Salvation work of Jesus was a one time event that happened in 33 A.D. for all believers.  Therefore it is called the Finished Work of Jesus.  Those who are truly saved by the power of God do not practice sin.  John wrote that those who say that they have no sin make God a liar!  Believers who sin must confess their sin or sins to God.  Confession within this context means to "agree" with God that one has sinned.