Zechariah 3:1 – Then the angel showed me Jeshua the high priest standing before the angel of the Lord.  Satan was there at the right hand, accusing Jeshua of many things. (NLT)
Being accused for something you did not do can be frightening.  If you are accused of committing a crime that you did not commit, your life suddenly seems to fall apart.  What is worse is if you get convicted, the criminal gets off scot free, while you wind up paying the time.
When it comes to our sin, we are guilty.  The moment we enter into this world, we have inherited the sin nature.  Sinners cannot see the kingdom of God.  Sin separates us from our heavenly Father, our Creator.  Jesus was sent to take our place.  He was wrongfully accused of crimes He did not commit, and paid the ultimate price.  But that was God’s plan and it works out in our favor.  In Christ, our guilt has been paid, so we are free.
However, despite that we are a new creation in Christ, Satan still accuses us.  He is notorious at tempting us ruthlessly and if or when we succumb to our sin, he immediately blames and attacks us for that very sin he attacked us with.  But remember, Jesus paid the penalty for sin and His infinite mercy.  We have been justified by Christ.