I know Satan and his minions can put thoughts in our minds but can he see what we are thinking?
We are told that our thoughts can only be truly discerned through the Spirit.
Yea, I tell thee, that thou mayest know that there is none else save God that knowest thy thoughts and the intents of thy heart. D&C 6:16 (emphasis added)
We see many examples throughout the scriptures of the Lord also allowing men to discern thoughts through the Spirit.
Now Zeezrom, seeing that thou hast been taken in thy lying and craftiness, for thou hast not lied unto men only but thou hast lied unto God; for behold, he knows all thy thoughts, and thou seest that thy thoughts are made known unto us by his Spirit. Alma 12:3 (emphasis added)
However, there are always counterfeits for most of God’s powers. In this case, the practice known as mentalism is one that should readily come to mind. Anything that man has been able to figure out, Satan already knows about it. And when it comes to something that requires practice to master, Satan has nothing but time to practice deception.
Mentalism is a broad term involving things as simple as reading facial expressions. But it also includes things like detecting breathing patterns, listening intently to vocal cues, reading the choices someone makes. The simple truth is that humans are generally very easy to read. But there are certain limits on how much one can discern through such observation.
Now take it to the next level. As a spirit, Satan can observe much more than simple outward expressions. He can detect heart rate. He can see blood flow to various parts of our bodies. He can see when some neurons are firing or not. He can detect low levels of muscle twitching and so forth. So, he seems to have somewhat of an advantage in the field of mentalism.
Then he can also see combinations of cues. As you stated, he can put thoughts into our minds. As we give place for them in our minds, then there will be some physiological reactions to such thoughts. If he knows the thought that went in, and then reads our body’s reactions to them, he can begin to form a profile for future reference.
This all seems pretty amazing or even powerful and it may seem he has an unfair advantage over us. But remember, this ability will have it’s limits. He may know you’re feeling fear. But it will be difficult to figure out what you are afraid of. You may feel great peace. But what thought is causing you to feel such peace?
And no matter what power he seems to have, you, as an embodied child of God, will always have power over the adversary. What will Satan be feeling as you choose righteousness? All he will see is that you’re feeling joy in righteous causes. How saddened and discouraged he must feel when we do so. As we choose righteousness, I would certainly hope he could read our minds and see the joy we receive from following the will of the Lord.