Pat007, thanks for writing.
There is no indication in the Bible that demons place thoughts in the minds of Christians. In the Gospels and Acts, demon-possessed people always tell the truth. They identify Jesus as the Holy One of God and as the Son of God. They identify Paul as a servant of God and a preacher of salvation (Acts 16.17). I'm not aware of a place where a demon is specifically identified as (1) deceiving people, (2) speaking something untrue, or (3) placing thoughts in the minds of Christians. If you know of such a text, we can discuss it.
Instead, demons in the Gospels wreak havoc on people's bodies and minds (like making them seem like madmen). But there is no evidence that they place thoughts in the minds of Christians.
Satan is different, however. As I mentioned in the thread above your question, to deceive someone means you have to have some influence over their mind and the way they think. You want some specific texts.
- In the temptation of Jesus, it seems that Satan is trying to influence how Jesus thinks.
- In Matthew 16.23, Jesus implies that Satan has placed this thought in the mind of Peter and turned Peter into an agent of Satan, functioning as a tempter and adversary—the role of Satan.
- In the temptation of Eve in Genesis 3, we could at least admit that Satan influenced the way she thinks by planting certain ideas and thoughts in her head.
- In Matthew 13.19, Satan snatches away the Word that was sown. It implies some influence over what we think and the way we think, since "planting the seed" implies thoughts of the mind and heart.
- In Acts 5.1-3, Peter accuses Ananias that Satan has filled his heart, for one, and incited him to lie.
This is a great question you had. If you want to talk it more, let's talk.