The excellent website Roman Catholic Spiritual Direction has a Q & A about Demonology which draws on the work of exorcist Fr. Fortea, author of Interview with an Exorcist. The most recent post looks at the question, What does a demon think about?
A: Every demon retains the intelligence of its angelic nature. Demons know and inquire with their minds about the material and spiritual worlds, the real and conceptual worlds. As spiritual beings, demons are eminently intellectual; there is no doubt that they are deeply interested in conceptual questions. They know very well that philosophy is the most elevated of the sciences and that theology is built upon philosophy. In spite of this knowledge, every demon hates God.
Though demons find pleasure in knowing, they also suffer as a result of their knowledge—especially when this knowledge leads them to think about God. Demons constantly perceive the order and beauty of the Creator in all created things. Even in apparently neutral things, they see the reflection of the divine attributes.
Demons are not constantly engaged in tempting human beings. Much of the time they spend thinking. They suffer during those moments when they remember God and become conscious of their miserable state, that is, their separation from God. As we have previously noted, the amount of this suffering varies in intensity according to each demon’s degree of moral deformation.
Protect the Pope comment: Our Lord Jesus Christ indicates what demons think about in the Gospels:
‘He was a murderer from the beginning and does not stand in the truth, because there is no truth in him. When he lies, he speaks according to his own nature, for he is a liar and the father of lies.’ (John 8:44).
It follows from this revelation that demons think about murder and spreading lies, and spreading lies about murder. The greatest lie about murder is the unquestioned acceptance of abortion as a good to justify the killing of millions of unborn children every year. The rage and violence heaped on Christians when we challenge this lie is another sign of the demonic influence motivating the killing of babies through abortion.
There is one name that will defeat this evil scourge across the world, and that name is our Lord Jesus Christ. If every Catholic priest in the world called on the name of Jesus Christ everyday to end the crime of abortion the pro-life movement would be unstoppable.