1 Corinthians 2:10-16
Is it possible for a human to know the mind of the Lord? Definitely! Jesus Christ, in his human nature, knows the will of the Father. But can a merely human person know the will of God? St. Paul answers yes. “We have the mind of Christ.” This is because the Holy Spirit lives within us. We received the Spirit from God so that we might know the things that were freely given to us by God.
This is why the Holy Spirit is called “the Holy Spirit”. Our relationship with the Father is like a human’s relationship with God, completely beyond words or knowledge. Our relationship with the Son is human to human, face to face, in human words. Our relationship with the Holy Spirit is human to spirit. Ancient people knew what that meant because they had often seen possessions by evil spirits.
Not that it is exactly the same. The difference between how the Holy Spirit dwells in us versus how the evil spirits possess a person is as enormous as the difference between the Holy Spirit and the evils spirits. The evil spirits, once they possess a person, control them against their will. The Holy Spirit gives us power and knowledge but never forces us. Spirits cannot enter without permission, but evil spirits will take anything as a pretext: dealing with magic or fortune-telling or choosing a life of sin or hating God. The Holy Spirit only enters through the Sacraments, with our explicit permission.
Modern people disregard magic and fortune-telling because we do not believe that they are real, but the evil spirits are able to work acts of power. The evil spirit in the Gospel today has knowledge. He sees Jesus and recognizes him. Evil spirits can do impressive things and share secret knowledge, but remember, they hate us. Anything they do or tell us is for the purpose of harming us. They enter into people to use them for their purposes. The Holy Spirit, however, loves us. His acts are always for our good, what he teaches us helps us, and he does not act unless we cooperate. We do not want the evil spirits no matter what their power is. We want the Holy Spirit, even though his presence is hard to see. He does not shout or push, since this would take away our free will, but if we cooperate, he will do amazing things.