What some folk need to understand about Jesus work on earth is that; SIN IS A SPIRITUAL THING, It all started with as man disobeyed God, it was a cause of the devil and this earth is where the devil rule and reign.
Now as a believer u confess Christ as your Lord and Saviour because of the spiritual sacrifice Christ did to save humanity for on sin, according to 1corinth. 15:3-4 (3. For I delivered unto you first of all that which I also received, how that Christ died for our sins according to the scriptures 4. And that he was buried, and that he rose again the third day according to the scriptures).
Romans 10:9 (That if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved). So therefore if any man be under the grace of Christ, Sin and it's spiritual effect does not have power over such man. As a true believer or follower of Christ he shall continually walk in righteousness and not that he doesn't sin but he's covered by grace of Jesus Christ, because no man can be totally righteous in this life that the devil controls. A true christian will not sin wilfully.