18 We know that whosoever is born of God sinneth not; but he that is begotten of God keepeth himself, and that wicked one toucheth him not.
The BLOOD of Christ covers and cleanses every believer so that their sin is never sin by the FATHER! THAT is why John can say that we sin not... We sin every day but Jesus has cleansed our and paid for our every sin!
Also, because the HOLY SPIRIT of GOD has both sealed every believer and indwells every believer, and "greater is HE that is in thee than he that is in the world", Satan touches not the believer..... We are KEPT by the POWER of GOD!