Demons apparently are quite intelligent about matters of theology and practice. They are monotheists (that is, they believe that one supreme God exists), though the history of demonic influence shows that they propagandize false belief in imaginary pagan deities. They hold belief
in the identification of Jesus as God’s Son, as shown in their confession in Matthew 8:29. They certainly believe in the existence of moral standards and in God’s final judgment concerning evil. So, in many ways, demons believe biblical thruth.
They have seen the truth close up, and their entire job is to subvert it. You have to know the opposition, so to speak. The demons’ seemingly orthodox beliefs demonstrate that simply knowing the truth does not bring peace with God. Submitting to the truth and living in obedience to it is the key. To believe in God means to act on the truth one possess. That simple difference separates Christian faith from demon opposition.
JAMES 2:19 – 19. Thou believest that there is one God; thou doest well: the devils also believe, and tremble.