Ephesians 2:6:

And [God] hath raised us up together, and made us sit together in heavenly places in Christ Jesus:

Notes on Ephesians 2:6:

If the Body of Christ would just understand this one concept, there would be a lot less sickness.  As far as God is concerned, you rule and reign with Jesus Christ in this life.  (Paul also said that you will reign in life through Jesus Christ in Romans 5:17.)  You sit with Christ, far above the devil and all his cohorts.  You have authority over the devil.  You don’t have to sit there and let the devil oppress you with sickness.  You can put a stop to it.  The devil is way, way, below you because you’re seated with Christ FAR above him!   You need to start acting on that reality and stop putting up with the garbage that the devil tries to get you to “just live with.”

See also:

Notes on Ephesians 1:15-23
God’s Power Toward You
Paper Roadblocks to Healing
How to Deal with the Devil
Who You Are and What You Have
Free Access to the Throne!
Ruined Righteousness
Do We Already Have Healing in Our Born-Again Spirits?
Should We Plead the Blood when Dealing with Demons?
Is Deliverance a Dangerous Practice Best Left to Trained Exorcists?