Luke 4:34

Saying, Let us alone; what have we to do with thee, thou Jesus of Nazareth: are thou come to destroy us? I know thee who thou art; the Holy One of God.  

Does it not amaze that people will put more stock in evil spirits than a reality of God?  The devils knew precisely who Jesus was on a spiritual level.  He also knows exactly who we are on a spiritual level.  That is why the devil does not want a Christian to grow in the word and speak the word.  We have power over the spirits, just like Jesus, and we can use that power.