Dear Father,
how can we be sure that our actions are truly pleasing to God?
In addition, we know that even demons can perform miracles and pass them off as divine miracles.  

Priest’s answer

Dearest,
1. we cannot have absolute certainty while we are on this side of life.
The Council of Trent says that “no one can know with a certainty of faith, which cannot be subject to error, that he has obtained the grace of God” (DS 1534).

2. However, as Saint Paul reminds us: “The Spirit itself bears witness with our spirit that we are children of God” (Rom 8:16).
This we do not perceive from outside sources, but “but through the effect of filial love he produces in us.” (S. Thomas, Commentary on Romans, 8:16). 

3. Filial love manifests itself in the generous and full observance of His commandments and in the state of mind that makes exposing ourselves to any circumstance preferable to offending the Lord.
Jesus said: “Whoever has my commandments and observes them is the one who loves me.” (John 14:21).
Saint Thomas comments: “Note that true love is love which appears and proves itself by actions: for love is revealed by its actions. Since to love someone is to will that person something good and to desire what this person wants, one does not seem to truly love a person if he does not accomplish the will of the beloved or do what he knows this person wants. And so one who does not do the will of God does not seem to truly love him.” (S. Thomas, Commentary on John, 14:21).  

4. Regarding the possibility that demons can perform miracles we have to clarify what is meant by miracle.
Saint Thomas defines a miracle as something that is performed with power superior to that of any creature and therefore can only be performed by God (see Summa Theologiae, I, 110, 4).
When we say “any creature” we imply not only mankind, but also angels.
Regarding angels, we need to remember that demons are angels. Their rebellion to God made them into demons, but their angelic nature remains unchanged.
Therefore, anything that the good angels can do, the rebel angels can also do – within the limits of divine permission. 

5. Therefore, for example, as angels can produce a body to make themselves manifest, so can demons.
Similarly, certain phenomena that are outside of human ability, such as levitation, which consists in being suspended in the air without any material support, that we read about in the lives of certain saints, might also happen during a seance, where demons have been – directly or indirectly – summoned.
In the same way, episodes of levitation supposedly happen within the fakirs, oriental people dedicated to asceticism.
Since these forces are not outside of nature, even though we don’t understand them, these phenomena cannot be classified as miracles, but rather prodigies. 

6. Saint Thomas says: “miracles are those things which are done outside the order of the whole created nature. But as we do not know all the power of created nature, it follows that when anything is done outside the order of created nature by a power unknown to us, it is called a miracle as regards ourselves. So when the demons do anything of their own natural power, these things are called “miracles” not in an absolute sense, but in reference to ourselves. (Ib., I, 110, 4, ad 2).
“Some miracles are not true but imaginary deeds, because they delude man by the appearance of that which is not; while others are true deeds, yet they have not the character of a true miracle, because they are done by the power of some natural cause. Both of these can be done by the demons” (Summa Theologiae, II-II, 178, 2). 

7. Regarding miracles performed by the antichrist, here is what Jesus said: “False messiahs and false prophets will arise, and they will perform signs and wonders so great as to deceive, if that were possible, even the elect. Behold, I have told it to you beforehand.” (Matt 24:24-25).
Saint Paul as well, while talking about the end of the world, says: “For the mystery of lawlessness is already at work. But the one who restrains is to do so only for the present, until he is removed from the scene. And then the lawless one will be revealed, whom the Lord Jesus will kill with the breath of his mouth and render powerless by the manifestation of his coming, the one whose coming springs from the power of Satan in every mighty deed and in signs and wonders that lie, and in every wicked deceit for those who are perishing because they have not accepted the love of truth so that they may be saved.” (2 Ts 2:7-10).

8. Regarding this kind of miracles and prodigies, Saint Thomas makes the following distinction: “[…] if we take a miracle in the strict sense, the demons cannot work miracles, nor can any creature, but God alone: since in the strict sense a miracle is something done outside the order of the entire created nature, under which order every power of a creature is contained. But sometimes miracle may be taken in a wide sense, for whatever exceeds the human power and experience. And thus demons can work miracles, that is, things which rouse man’s astonishment, by reason of their being beyond his power and outside his sphere of knowledge. For even a man by doing what is beyond the power and knowledge of another, leads him to marvel at what he has done, so that in a way he seems to that man to have worked a miracle.
It is to be noted, however, that although these works of demons which appear marvelous to us are not real miracles, they are sometimes nevertheless something real. Thus the magicians of Pharaoh by the demons’ power produced real serpents and frogs. And “when fire came down from heaven and at one blow consumed Job’s servants and sheep; when the storm struck down his house and with it his children—these were the work of Satan, not phantoms” (Summa Theologiae I, 114, 4), as Saint Paul advises: “the one whose coming springs from the power of Satan in every mighty deed and in signs and wonders that lie” (2 Ts 2:9).
True miracles, on the other hand, can only be performed by divine virtue. 

I bless you, wish you the best and remember you in my prayers.
Father Angelo

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