Initial explanation: When talking about Satan, I mean Satan and the demons. Since Satan and the demons were created as angels - albeit now they are fallen angels - they are not able to be in more than one location at a time. So when the name Satan is spoken, it refers to Satan and the demonic realm, with Satan recognized as the leader. (In the same way we say General Patton won many battles, we recognize that Patton personally wasn’t the one doing the fighting, but he was the leader and, by referring to him, we mean all those who were under his leadership.) So I will only say “Satan,” but mean the entire demonic realm.
Also, since Satan is an angel, he has great intelligence and great power.
Questions to consider:
1. Can Satan plant thoughts in our mind?
2. Can Satan read our mind?
If Satan was able to plant thoughts in our minds, then he would indeed be able to make us sin, but there no place in Scripture where we see Satan making people sin. Even Adam and Eve were only tempted by Satan, but it is human free will choice that leads to sin, by choosing that which is against God.
The Scripture in many places speaks of the demonically-possessed. In these people the demon does exercise control to a great degree, but there is no indication that Satan plants thoughts in their minds, rather he uses the people as channels to express his own thoughts.
Contrary to much false teaching, a Christian cannot be possessed by demons because a Christian is in-dwelt by the Holy Spirit. 1 Cor. 3:16; 1 Cor. 6:17, 19; 2 Cor. 1:22; 2 Thes. 3:3; 1 Pet. 1:5; 1 John 4:4; 1 John 5:18.
Since God imbued man with a free will to choose between good and evil, it is not necessary for Satan to place thoughts in our minds. All that is necessary is for him to observe human behavior with his great intelligence and place known temptations in the path of mankind. After all, he has been observing humans for 6000 years!
Eccl. 7:29 says, “God made people upright, but they pursued many schemes.” (HCSB) James 1:14-15, in response to whether God tempts people, says this: “But each person is tempted when he is drawn away and enticed by his own evil desires. Then after desire has conceived, it gives birth to sin, and when sin is fully grown, it gives birth to death.” (HCSB) These passages certainly demonstrate that we don’t need Satan planting thoughts in our mind!
Can Satan read our minds? NO. This is not a power angels have been demonstrated to possess in Scripture. God has the ability to do so, and we know this from many passages of Scripture, but God is omniscient while Satan - as an angel - is not. However, since Satan is an extremely intelligent being and has been watching mankind for 6,000 years, he has great understanding as to how mankind thinks. He knows what can be used as temptations to awaken sinful desires in man.