Dear Gene,
Below is an extract of an reply from Ray to an question asked of him regarding demons and evil spirits.
http://bible-truths.com/email9.htm#wrestle ----------------------
[Ray Replies]
Dear Jim:
Well, just like almost everything else Christians adopt as truth, their knowledge of demons and spirits is equally eschew. First, Jim, always remember the basics:
"...for it is not ours to wrestle with blood and flesh, but with the sovereignties, with the authorities, with the world-mights of this darkness, with the spiritual forces of wickedness among the celestials" (Eph. 6:12).
So it is NOT the physical that is our biggest problem (flesh and blood), being overweight, etc.
Next we must understand that demons are FALSE DOCTRINES -- "doctrines of demons" Paul calls them. So anything that would influence us to believe in, follow, or be persuaded by any such things are demons influences.
So when we speak of "anger" we are in the realm of the spirit. James says, "Whosoever is ANGRY with his brother is a MURDERER"! WOW! "Be angry and SIN NOT -- do not let the sun go down upon your ANGER" is another.
So being overweight and having uncontrolled anger are two totally different things. Being overweight is no more a sin than having flat feet. There are thousands of things in the biological makeup of our bodies over which we have and nor can we have control. If one is a total glutton, that is a lust of the flesh, but MANY overweight people eat very little for their size. But anger, that's different. Anger comes from within the man and it can cause one to SIN.
Now then, what do we do with the demons of anger, lust, and other aberrant behavior, cast them out? Well, if all we had to do was "cast them out," we wouldn't have to "wrestle" with them, would we?
Satan and his demons have their role in God's creation. God Himself has even commissioned LYING spirits to go out and do their dirty work (I Kings 22:22). So demons are real, they are here, and they will be around for a long time.
How should we handle them -- ask the preacher to cast them all out so that we are clean and will never be bothered in any spiritual way again, not to mention having a perfect size body? No, here's what God tells us we should do after telling us that we DO WRESTLE against these forces:
"Therefore take up the panoply [armor] of God that you may be enabled to WITHSTAND in the wicked day, and having effected all, to STAND. STAND, then, girded about your loins with TRUTH [remember I said demons are FALSE doctrines], with the cuirass of righteousness put on, and your feet sandaled with the readiness of the evangel [gospel] of peace; with all taking up the large shield of FAITH, by which you WILL BE ABLE TO EXTINGUISH ALL THE FIERY ARROWS OF THE WICKED ONE."
So the truth is that we continue to wrestle and do battle with them -- it is good for us to do so, it MAKES US STRONG in the TRUTH and in our reliance of God's spiritual armor to protect us.
Hope that helps your understanding a little better.