Some Christians have the illogical belief that demons can't read people's minds, but humans have done research and invented devices that can read a person's mind with a lot of accuracy. Who do you think inspired and guided this research? Not the Holy Spirit.
Holy Spirit would not put that kind of power in the hands of unregenerate people. He knows exactly what people are thinking and, if He wills, reveals it to His servants via word of knowledge.
Humans who have researched the brain and subjected it to stimulation have used many images and events relating to sinful acts to gain their knowledge. Holy Spirit was not involved in this.
Demons have studied humans for thousands of years. They can register every biological change in our organs and see how we react to outside stimulation of our senses, as well as the thoughts that they interject into our minds. They know if porn or violence intrigues a subject or disgusts them.
Besides this, the demon that is assigned to us at conception knows every incident we have experienced, every word of conversation we've heard or spoken, every book we've read, every show we've watched, and how we've reacted. They can share that information with other demons that are assigned to afflict us.
If a demon cannot read our minds directly, they surely can make good guesses based on body readings and our past reactions. However, I think that they can read our minds, but I don't think that they can read the depths of our heart. Only God knows what is in the core of our being. The tests and trials of our lives reveal what is in our heart.
It has been said that the gift of tongues has been given to us because satan can't read minds and it keeps Holy Spirit's plans secret until He is ready to reveal them. I agree with the latter part of that statement. I also think that it keeps His strategies secret from us, until we are ready to know the details without being hindered by unbelief or the resistance of our flesh.
There are many times it was a good thing that I didn't know what God was going to let me go through to develop my character, or to achieve a goal. I would have been frightened or appalled and probably run in the opposite direction.
It's a good thing that we don't know everything that we're praying on behalf of others when speaking in tongues. We might judge them or be frightened for them. God doesn't give us the interpretation of what we've prayed until we're ready to know and respond correctly.
You can be sure that the demons know quite a lot of times what we've prayed because angels are sent through our praying in tongues to afflict them and drive them away. We might not be aware that we prayed for our child's school teacher and helped them make a decision that protected the children, rather than indoctrinate them with antichrist values, but the demon that was assigned to make sure the teacher presented the material knows that someone prayed and caused them to fail its mission.
Its commanding officer punishes the demon for its failure, but is also interested in tracking down the Christian who caused the disruption. Praying in tongues keeps the angels engaged in dealing with demonic attempts to avenge themselves on us, while keeping us blissfully ignorant of things that we don't need to know, unless God wants to reveal them.
Do we have to pray out loud in order to receive answers to our prayers? Some say that we have to because the Bible demonstrates that people pray out loud. Yes, but it also demonstrates that God answers prayers that aren't prayed out loud, such as when Abraham's servant asked for a sign to help him know the right girl that Isaac was supposed to marry. He told Rebekah's family that he spoke the prayer in his heart. Nehemiah quickly prayed in his heart when he answered the king as to why he looked sad. When Hannah prayed for a child and promised to give him to God, Eli, the High Priest, thought she was drunk because her lips moved, but her prayer was silent. Either way, God answers prayers whether spoken out loud or said within the heart. Most of time, I don't speak my prayers out loud, unless I feel led of the Holy Spirit to do so.
There are times when I am on the bus or walking down the street that I see a need that requires prayer, and I don't delay to send up a prayer right away, silently within my heart. It is the only way that I can get relief from the agitation I feel about a situation, or relief from a burden of compassion. God hears what is going on in my heart and His angels see my prayers streaking up to Heaven with rays of rainbow light. Jesus said it is the Pharisees who like to say their prayers out loud on the street, so that the people around them can see their devotion to holiness.
Even when I am at home, I rarely pray out loud. Why should I? God can hear me when I pray in my heart and it saves my voice from getting overused. I'm always engaged in some kind of prayer, though not very often in petition or intercession. My thoughts are a conversation with God, either putting questions to Him or listening to His answers or guidance, delighting myself in Him and trusting that He will give me the desires of my heart in regards to the needs of other people, of animals, of my own personal needs and wants, or in regards to the environment. I usually don't speak my conversations with God out loud.
Illegal listening devices convey to human ears what they have no right to know. I might not think that I'm important enough to have my conversations or actions recorded, but some weasel in a surveillance agency might decide to monitor me. If I pray silently, they are likely to be bored out of their mind watching me, which serves them right. If God leads me to pray out loud, though, I don't worry about what the enemy, whether they are human or demonic, might learn.
Listening devices, Lanny? Are you serious? Hey, if you don't know that governments think that they have to gather every possible piece of information on people to keep them under control, then you're sadly out of touch with reality. Not just your own government, but enemy governments, as well. My laptop was made in China; I didn't realize that until after I bought it, and then I read online that the manufacturers probably monitor everything that is done on it.
If you have a cell phone, it can be switched on remotely and every conversation you have in the same room as your cell phone can be monitored. If you have a landline, conversations can be listened in through the phone jack. That technology has been in place for years. Just be sure that, if you're a Christian, you explain every now and then how souls can be saved, for the benefit of anyone who decides to review what has been recorded.
Do I worry about surveillance? Nope. I just live my life. I walk around my home in my underwear sometimes when the curtains on my windows are closed. I've taped over the camera on my laptop. I've done my duty towards modesty, but if there is a camera that I don't know about recording me in my underwear, or without it, I doubt that anyone who reviews the tapes will get a thrill.
One of the things that gives me peace about surveillance technology is an inner vision God gave me years ago. There was a meeting going on where gold dust was falling and I saw it even on a beetle in the room. God's word to me was that His glory was coming and that it is going to also fall on His enemies who are bugging the meetings.
Corrie Ten Boom saw this opportunity many years ago, on her visits behind the Iron Curtain. She was not allowed to preach the Gospel when she met with believers in their state–approved churches, but when she was at her hotel, she realized it was bugged. She looked for the device in her room and then preached into it to the communist soldiers who were listening in. Hallelujah!
Demons can monitor our thoughts, but what we need to care about is monitoring our thoughts ourselves and taking every thought captive that is not pleasing to God. Any thought I have that is contrary to the Word of God, or just simply some useless, random thought that has no business being in my mind, I bind it in the Name of Jesus, and then I say in my heart, "I bring this thought to my Daddy to take care of it."
My Heavenly Father deals with the bullies who interject thoughts into my mind. Some of them are really disgusting, but even if it found access to my mind because of sinfulness in my flesh, there is no point in trying to hide it from God. He sees everything. It is reassuring to know that He loves me, regardless, and He is pleased that I trust Him to deal with even the worst things in my sin nature.
I read that religion says, "I made a mistake; my father is going to kill me." Relationship says, "I made a mistake; I need my Dad!"
When I bring a captive thought to the Lord, I picture it like a brick that I lay at His feet. I imagine a little pedal near His foot and when He taps it with His toe, a trap door opens and the brick goes tumbling down through the second heaven, knocks the demon on its head who sent the thought, and both brick and demon fall down into Hell, where the demon gets a beating for having failed to make his evil thought stick to me. Yay!
When I do this with my thoughts, usually I stop thinking about the disturbing thought right away as peace floods through my heart. If that doesn't happen right away, I just do the exercise over a few more times until the desired result is achieved. It also helps to recall Scripture verses that combat the specific thought, or I set my mind on looking to Jesus and drinking in His divine essence. That is bliss.
If I am involved in doing something where I can't stop and put myself through my normal way of capturing a thought, I just surrender the intruding thought in an instant to my Heavenly Daddy. He understands and deals with it.
Until I started capturing thoughts in this literal way, I didn't realize how much closer it brings me into relationship with the Father. It gives me a greater sense of His protectiveness towards me. So many times, I have sensed His anger towards the thought and the interfering demon that sent it, but never towards me because I trust Him and demonstrate this by bringing every erring thought captive to Him, no matter how appalling I find the thought.
Psalm 51:6, "Behold, you desire truth in the inward parts: and in the hidden part you shall make me to know wisdom."
Proverbs 20:27, "The spirit of man is the candle of the LORD, searching all the inward parts of the belly."
Your word have I hid in my heart, that I might not sin against you.