The best way to understand what we mean by our profession of faith in the Holy Spirit is to compare it with our faith in the Son of God. In God there is intellect and will, corresponding to thinking and loving in human beings. Scripture identifies the mind of God with the Word of God, as St. John tells us: “In the beginning was the Word, and the Word was with God, and the Word was God” (John 1:1). “So, just as the Word of God is the Son of God, so the Love of God is the Holy Spirit” (St. Thomas Aquinas. Exposition of the Apostles’ Creed, Article 8).

That is why we can say that a person has the Holy Spirit when he loves God. St. Paul tells us that, “The charity of God is poured forth in our hearts by the Holy Spirit who is given to us” (Romans 5:5).

Over the centuries there were those who had the erroneous idea that the Holy Spirit is a mere creature. They believed He is less than the Father and the Son; in fact, that He is God’s servant and minister. That is why from earliest times the Church added no less than five articles to the Creed about the Holy Spirit.

Given the importance of this subject, it is worth comparing the Holy Spirit with the different kinds of created spirits that we believe exist in the world, and see how the Holy Spirit is unique as the Third Person of the Holy Trinity.

There are first of all created spirits that are angels. They are “all ministering spirits” (Hebrews 1:4). But the Holy Spirit is not the created spirit of the angels: The Holy Spirit is Divine. John tells us “God is a Spirit” (John 2:24), and St. Paul says that “The Lord is a Spirit” (II Corinthians 3:17). That is why when the Holy Spirit is given to us, we are able to love God so freely as to sacrifice voluntarily the selfish love of the world: “Where the Spirit of the Lord is, there is liberty” (II Corinthians 3:17). Our faith in the Holy Spirit is our belief that God, who is Love, can share with us something of His own divine love.

There are also the created spirits that are human souls. Our souls give natural life to our bodies. They are immediately created by God out of nothing at the moment of our conception, and infused into our bodies from the first moment of our human existence in our mother’s womb. But just as these created spirits give natural life to our bodies, the Holy Spirit conferred at baptism gives supernatural life to our souls. The Holy Spirit is the Uncreated Grace whose indwelling in our souls gives us sanctifying grace, which the Church allows us to call the soul of the soul. The Third Person who dwells in our souls is the Lifegiver whom Christ said would abide in us, provided we believed in the Savior’s words (John 6:63).

If we ask, who exactly is the Holy Spirit? we must say He is one in substance with the Father and the Son. No less than the Son is the Wisdom or the word of God, so the Holy Spirit is the Love of the Father and the Son. He therefore proceeds from both. Even as God’s Wisdom is of one substance with the Father, so God’s Love is one in substance with the Father and the Son. In the Nicene Creed we say, “We believe in the Holy Spirit, the Lord, the giver of life; He proceeds from the Father and the Son.” The closing phrase, “and the Son” in Latin reads Filioque, and has made doctrinal history. It was inserted with papal approval to counteract the heresy that claimed the Holy Spirit proceeds only from the Father. Since the thirteenth century, the Filioque has been one of the chief grounds of opposition by the Eastern Orthodox Church to the Church of Rome.

Given the perfect equality of the Holy Spirit with the Father and the Son, He is to be equally worshipped with the First and Second Persons of the Trinity. That is why St. John declares that “true adorers shall adore the Father in Spirit and in Truth” (John 4:23). That is also why Christ told His disciples to “teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Spirit” (Matthew 28:19). The three Persons of the Trinity have only one Divine Name, since they have only one Divine nature. Finally, that is why the Nicene Creed adds the statement about the Holy Spirit, “who together with the Father and the Son is equally adored and glorified.”

Sacred Scriptures teach us that the Holy Spirit is equal to God. We know that the ancient prophets spoke on behalf of God. St Peter tells us that, “The holy men of God spoke inspired by the Holy Spirit” (II Peter 1:21). That is why the Nicene Creed also adds the sentence, “He spoke through the prophets,” referring to the Holy Spirit. Again, in reprimanding Ananias for deceitfully withholding some of his property from the Christian community, Peter asked him, “How can Satan have so possessed you that you should lie to the Holy Spirit?…It is not to men than you have lied, but to God” (Acts 5:3, 5).

Our Catholic religion is filled with professions of faith in the influence of the Holy Spirit in our lives. We speak of the gifts of the Holy Spirit as the supernatural instincts or impulses that urge us to put the virtues of faith, hope, and charity into practice. We have the fruits of the Holy Spirit that give us a deep supernatural satisfaction in doing the will of God. But more specifically, the Church identifies certain ways in which the Holy Spirit enters our lives.

He cleanses our souls from sin. This follows logically from the fact that the same One by whom our souls were created is the One by whom they are to be repaired. Since it was through the love of God that human souls were made, this same Love, who is the Holy Spirit, must restore souls to His divine friendship.

The Holy Spirit enlightens our minds. Whatever we know by faith, we have received by the power of the Spirit. This is what Christ meant when He promised the “the Holy Spirit, the Paraclete [Advocate] whom the Father will send in my name, will Himself teach you all things and will bring all things to your mind, whatsoever I shall have said to you” (John 14:26). Christ was the first Advocate who revealed the mysteries of God. The Holy Spirit is the second Advocate who enables us to understand what Christ had revealed.

The Holy Spirit enables us by His grace to observe the divine commandments. As God foretold in the Old Testament: “I will put my Spirit in the midst of you. I will cause you to walk in my commandments and to keep my judgments and do them” (Ezekiel 36:27). Except for the power of the Holy Spirit, sent by Christ, we could not live up to the humanly impossible demands of the Savior on His followers.