According to Catholicism, can Satan read lips?

Generally speaking is Satan and/or the Demons capable of reading lips when we speak.

What if we simply mouth our prayers while we are praying?

Can he read our lips while we are praying aloud in Jesus's name?

This question was inspired by a comment in this question.

  • Now, slowly scientists can translate brain signals into words based on what frequencies is the brain synapses producing. If the spiritual beings can see these frequencies they might be able to understand very well what you are thinking. This is why I think mental prayer of a high degree such as prayer of simplicity and higher can be accessible only to God as no words, thoughts are always produced..
    – Grasper
    Mar 16, 2022 at 15:54
  • Thanks, Grasper. Your observations would justify my answer below (though down-voted !). Mar 17, 2022 at 8:51

3 Answers 3


I would expect it to be difficult to uncover much scholarly material on a question as specific as this one. Nevertheless I'll try.

In Deliverance Prayers for the Laity from Sensus Traditionis Press there is a "Binding Prayer to Blind the Demons" which reads as follows:

Most gracious Virgin Mary, thou who wouldst crush the head of the serpent, protect us from the vengeance of the evil one. We offer our prayers, supplications, sufferings and good works to you so that you may purify them, sanctify them and present them to thy Son as a perfect offering. May this offering be given so that the demons that influence us (could influence us or name the person) do not know the source of the expulsion and blindness. Blind them so they know not our good works. Blind them so that they know not on whom to take vengeance. Blind them so that they may receive the just sentence for their works. Cover us with the Precious Blood of thy Son so that we may enjoy the protection which flows from His Passion and Death. We ask this through the same Christ Our Lord. Amen.

This would suggest to us that the demons have a certain level of knowledge about our actions. It remains to ask, to what extent.

Since demons are angels by nature, they have an intellect and a will but no body. Therefore, unlike humans, they do not come to knowledge of a thing by first seeing it with the senses.

I haven't all looked through Dominion by Fr. Chad Ripperger, but in it he discusses demonic knowledge. Skimming through, I don't see an explicit mention of whether demons know our operations at a given moment (e.g. the movement of our lips) but it does seem like he and Fr. Jose Fortea write as though taking for granted that demons do have a knowledge about the bodies of a particular human at a given moment, and that this is how they make guesses about what we're thinking.


Yes, even more so than a human can.

Discussing the angels' knowledge of material things, q. 57 of the Summa Theologica's Treatise on Angels, St. Thomas Aquinas writes (a. 4 "Whether angels know secret thoughts?" co.):

A secret thought can be known […] in its effect. In this way it can be known not only by an angel, but also by man; and with so much the greater subtlety according as the effect is the more hidden. For thought is sometimes discovered not merely by outward act, but also by change of countenance; and doctors can tell some passions of the soul by the mere pulse. Much more then can angels, or even demons, the more deeply they penetrate those occult bodily modifications. Hence Augustine says (De divin. daemon.) that demons "sometimes with the greatest faculty learn man's dispositions, not only when expressed by speech, but even when conceived in thought, when the soul expresses them by certain signs in the body"; although (Retract. ii, 30) he says "it cannot be asserted how this is done."


See an excerpt from The Guardian of 11.7.2006:

An Italian lip-reader last night claimed to have deciphered the words Marco Materazzi said to Zinédine Zidane that provoked the French captain into butting him in the chest during Sunday's World Cup final, the great midfielder's final act before a red card ended his career in top-level football. According to the BBC, Materazzi said, "I wish an ugly death to you and all your family," and then told Zidane to "go #@$% yourself".

Well, lip-reading is important to the extent language is used in communication. But, does our thought process involve the spoken languages like English and French ? How does a babe think before it learns its mother-tongue ? Let us recall Helen Keller who was both blind and deaf. She, as a child, had understood water' as that wonderful cool something' before the day her instructor put her little hand under a small stream of water and very slowly wrote `w-a-t-e-r" on her palm.

The stupendous ability of human brain to encode and decode information (which is received in hundreds of units per second, through the senses and stored in billions of brain-cells called neurons)surpasses that of a computer. It is not necessary that the process involves spoken languages. The Creator, of course, can read the thoughts(and prayers) of a person even before they are given shape through spoken languages:

For the word of God is alive and active. Sharper than any double-edged sword, it penetrates even to dividing soul and spirit, joints and marrow; it judges the thoughts and attitudes of the heart(Hebrew 4:12).

But, what about the Devil? Has he been delegated such a faculty? It is a matter of debate. So, the answer to the question " Can Satan read lips ? " is : If God permits, Satan can read our thoughts even before they reach our lips.

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