Dear brothers and sisters, good morning!

With today's catechesis, we move from what has been revealed to us about the Holy Spirit in Holy Scripture to how He is present and at work in the life of the Church, in our Christian life.

During the first three centuries, the Church did not feel the need to explicitly formulate its belief in the Holy Spirit. For example, in the oldest Creed of the Church, the Apostles' Creed, after proclaiming: "I believe in God the Father, creator of heaven and earth, and in Jesus Christ, who was born, died, descended into hell, rose again and ascended into heaven," it adds: "[I believe] in the Holy Spirit," nothing more, without any further explanation.

But it was heresy that prompted the Church to clarify its faith. When this process began—with Saint Athanasius in the fourth century—it was the Church's experience of the sanctifying and divinizing action of the Holy Spirit that led the Church to the certainty of the Holy Spirit's full divinity. This occurred at the Ecumenical Council of Constantinople in 381, which defined the divinity of the Holy Spirit in the well-known terms that we still repeat today in the Creed: “I believe in the Holy Spirit, the Lord, the giver of life, who proceeds from the Father and the Son, who is worshiped and glorified with the Father and the Son, who spoke through the prophets.”

To say that the Holy Spirit “is Lord” is to say that he shares in the “Lordship” of God, that he belongs to the world of the Creator and not to that of creatures. The strongest affirmation is that he is entitled to the same glory and worship as the Father and the Son. This is the argument of equality in honor, dear to Saint Basil the Great, who was the principal architect of this formula: the Holy Spirit is Lord, he is God.

The conciliar definition was not an end point, but a starting point. Indeed, having overcome the historical reasons that had prevented a more explicit affirmation of the divinity of the Holy Spirit, it would be serenely proclaimed in the worship and theology of the Church. Already, Saint Gregory of Nazianzus, in the aftermath of this Council, would affirm without ambiguity: “Is the Holy Spirit then God? Certainly! Is he consubstantial? Yes, if he is truly God” (Oratio 31, 5.10).

What does the article of faith we proclaim every Sunday at Mass tell us, believers today? I believe in the Holy Spirit. In the past, it was primarily the affirmation that the Holy Spirit "proceeds from the Father." The Latin Church quickly expanded on this affirmation by adding, in the Creed of the Mass, that the Holy Spirit "also proceeds from the Son." Since the expression "and from the Son" is "Filioque" in Latin, this gave rise to the controversy known by that name, which has been the reason (or pretext) for so many disputes and divisions between the Eastern and Western Churches. It is certainly not our intention to address this issue here, which, moreover, in the climate of dialogue established between the two Churches, has lost the bitterness of the past and now allows us to hope for full mutual acceptance, as one of the principal "reconciled differences." I like to say this: "reconciled differences." Among Christians, there are many differences: this one belongs to this school, that one to another; this one is Protestant, that one... The important thing is that these differences are reconciled, in the love of walking together.

Having overcome this stumbling block, we can now appreciate the most important prerogative for us, proclaimed in the article of the Creed, namely, that the Holy Spirit is "life-giving," that is, he gives life. We ask ourselves: what kind of life does the Holy Spirit give? In the beginning, in creation, the breath of God gave Adam natural life; from a clay statue, he made him "a living being" (cf. Gen 2:7). Now, in the new creation, the Holy Spirit is the one who gives believers new life, the life of Christ, supernatural life, as children of God. Paul can exclaim: "The law of the Spirit of life in Christ Jesus has set you free from the law of sin and death" (Rom 8:2).

Where, then, is the great and comforting news for us? It is that the life given to us by the Holy Spirit is eternal life! Faith frees us from the horror of having to admit that everything ends here, that there is no redemption for the suffering and injustice that reign supreme on earth. Another saying of the Apostle assures us of this: “If the Spirit of God, who raised Jesus from the dead, dwells in you, he who raised Christ Jesus from the dead will also give life to your mortal bodies through his Spirit who dwells in you” (Romans 8:11). The Spirit dwells in us; he is within us.

Let us cultivate this faith also for those who, often through no fault of their own, are deprived of it and struggle to find meaning in life. And let us not forget to thank the One who, through his death, obtained this invaluable gift for us!