Each one of us has a built-in microphone that we use to turn unspoken words (thoughts) into words. Our microphone has a wiring system that leads to its speaker, namely, our mouth. This microphone, which is none other than the mind of our spirit, can be commandeered and used by the mind of an alien entity to the detriment of ourselves and those at the receiving end.
If your mind is not transformed to a state of complete renewal so that you speak your mind in accordance with the will of God, then righteousness, peace and joy will not always be in the sound of your voice. Your microphone (mind) is held in the hand of your spirit and it extracts from the contents of your heart whenever situations and circumstances call for an utterance. The heart - the place God looks at - can be honest or deceitful, depending on what it has been filled with from the world we live in. This is where all our thoughts take place and by listening to your heart, your mind - the microphone of your spirit - conveys it to the listener. "For as he (man) thinketh in his heart, so is he." (Prov. 23:7)
However, there are spiritual forces at play in the spirit world standing ready to intercept and inject a few words of their own into that microphone, using your very own mind to speak it. While incapable of knowing the thoughts of your heart, they certainly have thoughts of their own. Now here is the problem. Your mind is like a master of ceremonies. It states what suits the occasion and to do that it had to be fed with information beforehand. If the information is from the enemy and not from your own heart, your mind (the microphone held in the hand of your spirit) can cause considerable damage to your walk in the faith.
It has to be borne in mind that we are spiritual beings clad in physical bodies. Job spoke from his spirit when he said, "You have clothed me (my spirit) with skin and flesh, and have fenced me (my spirit) with bones and sinews." (Job 10:11,) This was the mind of the spirit of Job making this statement. He certainly had God-given knowledge of the make-up of man.
Demons are disembodied spirits seeking physical bodies to possess and control. They cannot possess your body unless you give them permission to do so by your words and deeds portraying your willingness to side with evil. It is tantamount to laying down a welcome mat to an open door. Furthermore, evil spirits, like any spirit good or bad, have no problem moving through solid objects - your own physical body included. We are all spirit-beings living in a spirit world, but man is designed to experience only the physical product of the spirit world. God is a Spirit and He created the physical world to which man is confined.
It stands to reason then, that agents of Satan can whisper prepared agendas to your spirit which your mind picks up as a thought.
Now here's the thing. Whatever is absorbed by your mind becomes stored in your heart as information and memory, ready to be mulled over and "microphoned" when the chief executive officer of your heart (your mind) decides to transfer it to a world of human listeners.
The point? If you are a mature Christian having made substantial progress in being conformed to "the image of His Son" (Rom.8:29) and "the mind of Christ" (1 Cor.2:16) holds sway over your own mind, then you would be in a strong position to recognize and withstand the wiles of the devil, but if you are a believer still drawn to the world and its attractions, be alert - there are unseen agents of destruction wanting to grab your microphone.