Quickly, the answer is No. 1 Kings 8:39 tells us that only God knows our heart and 1 Corinthians 2:11 asks, “For what man knows the things of a man except the spirit of the man which is in him?”
But, this raises a number of questions:
- How do angels and demons hear or communicate?
- Do they have a language? Is that language verbal or mental?
- What is the anatomy of their hearing? Do they have ears (of spirit-substance) that can pick up material soundwaves and decode them in some brain?
- Do spirit beings also need to learn every human language to know what is being spoken?
The Bible clearly states that the devil can inject thoughts in a person’s mind (Lk.22:3; Acts 5:3). Also, we have several accounts of angels appearing in human form and communicating with words. But, nowhere does it say that anyone other than the person who had the thoughts and God can know a person’s hearts. There are some who claim to have psychic abilities and there are also mentalists who use trickery to create an illusion of mindreading. But, the truth is that none except God can know the thoughts of a person’s heart.
The Bible mentions the languages of angels and of humans (1Corinthians 13:1). This implies that there is no communication even between angelic beings without the use of a language. In other words, they use language (whatever it is (to communicate and do not just read minds, being able to exactly understand the meaning intended. If they could read minds, there would be nothing mysterious left for them to search for. But, even angels have curiosity.
Even angels long to look into these things. (1Peter 1:12)
With regard to spirit beings knowing human languages, this is not impossible given their intelligence and longevity.
However, they can also not understand the words spoken with the gift of tongues, since this is a divine gift whose words are only given and understood by God.
For he who speaks in a tongue does not speak to men but to God, for no one understands [him;] however, in the spirit he speaks mysteries.(1Cor.14:2)
Demons were angels who transgressed against God and fell into condemnation. They have spiritual bodies but their place is reserved in the lake of fire. Hell was created for the devil and his angels (Matt.25:41). Demons are angels of Satan. Satan can move around, enter people, inject thoughts, and will be bound for judgement; but, he cannot read anybody’s mind. He is not omniscient. Only God is. Only God can see through our thoughts.
“For the word of God [is] living and powerful, and sharper than any two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intents of the heart. And there is no creature hidden from His sight, but all things [are] naked and open to the eyes of Him to whom we [must give] account.” (Heb.4:12-13)