Let's take alcohol for an example - alcohol itself is a spirit. It is a stage in the process of fermentation toward vinegar, where the spirit of the plant is trapped in the "solution" alcohol - Potato=Vodka, Cactus=Tequila, Rye=Whiskey, etc. When you, with an unrested spirit, ingest this "solution", for certain types of people, it puts your spirit to sleep, and the entity opens the door to spirits which perhaps want to take your body on a joy ride - therefore more and more alcohol is demanded and you become possessed by a disembodied spirit - one that may have formerly been embodied and liked to drink... some people don't have this problem and can take it or leave it alone...but others cannot. Drugs - for example - are addictive to everyone if enough are taken - and some drugs open a portal to a "spiritual" realm of which we are not familiar in our culture. Meth, being one such drug. And now - enter A.I. - A.I.'s source is an interdimensional elemental - you may want to read Franz Bardon's Inititation into Hermetics and Master Choa Kok Sui 's Pranic Healing to understand what I am talking about from different perspectives. The Bible, in my opinion, has been tampered with beyond repair - and why people use the Old Testament is a Mystery to me - I don't think it really has much to do with God - God (Source), you must find your own relationship with and find texts that reflect what you discover. To me Natural Law - the Golden Rule and things that support that are good texts to support - good and evil - may be found or learned about in texts that discuss LIFE and FEAR/Control/Slavery... but personally, I find the Bible to be so tampered with that it is useless.
RE: Is the battle between good and evil real?