Our belief in the Holy Spirit was expressed from the earliest days of the Church in the Apostles Creed. When we pray it, we professes faith in the Holy Trinity — Father, Son (Jesus) and Holy Spirit. Part of that prayer states:

… I believe in the Holy Spirit, the holy Catholic Church, the communion of saints, …”
— Apostles Creed

The Apostles Creed was revised and expanded at the Council of Nicene (325 A.D.) and the new version was called the Nicene Creed. It is one of the prayers we use today at Mass. It states the following about the Holy Spirit

… I believe in the Holy Spirit, the Lord, the giver of life,
who proceeds from the Father and the Son,
who with the Father and the Son is adored and glorified,
who has spoken through the prophets. …
— Nicene Creed

The Holy Spirit and Jesus have a joint mission in the world. The Catechism of the Catholic Church (CCC) states:

“The One whom the Father has sent into our hearts, the Spirit of his Son, is truly God. Consubstantial with the Father and the Son, the Spirit is inseparable from them, in both the inner life of the Trinity and his gift of love for the world. In adoring the Holy Trinity, life-giving, consubstantial, and indivisible, the Church’s faith also professes the distinction of persons. When the Father sends his Word, he always sends his Breath. In their joint mission, the Son and the Holy Spirit are distinct but inseparable. To be sure, it is Christ who is seen, the visible image of the invisible God, but it is the Spirit who reveals him.”
— Catechism of the Catholic Church (CCC), 2000, para.689

“Jesus is Christ, “anointed,” because the Spirit is his anointing, and everything that occurs from the Incarnation on derives from this fullness. When Christ is finally glorified, he can in turn send the Spirit from his place with the Father to those who believe in him: he communicates to them his glory, that is, the Holy Spirit who glorifies him. From that time on, this joint mission will be manifested in the children adopted by the Father in the Body of his Son: the mission of the Spirit of adoption is to unite them to Christ and make them live in him . . .”
— CCC, 2000, para. 690

In the New Testament, the gospel of John, Chapter 14, we find Jesus reassuring his disciples that He would not abandon them.

The Advocate.

“If you love me, you will keep my commandments. And I will ask the Father, and he will give you another Advocate to be with you always,the Spirit of truth, which the world cannot accept, because it neither sees nor knows it. But you know it, because it remains with you, and will be in you.
— New American Bible, Revised Edition, 2011, John 14:15-17.

In John, Chapter 15, we find the following:

“When the Advocate comes whom I will send you from the Father, the Spirit of truth that proceeds from the Father, he will testify to me.  And you also testify, because you have been with me from the beginning.
— New American Bible, John 15:26-27.

Pope Francis addressed the presence of the Holy Spirit in our daily lives, in a homily on Pentecost 2021.

Pope Francis

HOMILY OF HIS HOLINESS POPE FRANCIS

St Peter’s Basilica
Solemnity of Pentecost – Sunday, 23 May 2021

“When the Paraclete comes, whom I will send to you from the Father…” (Jn 15:26). With these words, Jesus promises to send his disciples the Holy Spirit, the ultimate gift, the gift of gifts. He uses an unusual and mysterious word to describe the Spirit: Paraclete. Today let us reflect on this word, which is not easy to translate, for it has a number of meanings. Essentially, it means two things: Comforter and Advocate.

The Paraclete is the Comforter.

All of us, particularly at times of difficulty like those we are presently experiencing due to the pandemic, look for consolation. Often, though, we turn only to earthly comforts, ephemeral comforts that quickly fade. Today, Jesus offers us heavenly comfort, the Holy Spirit, who is “of comforters the best” (Sequence). What is the difference? The comforts of the world are like a pain reliever: they can give momentary relief, but not cure the illness we carry deep within. They can soothe us, but not heal us at the core. They work on the surface, on the level of the senses, but hardly touch our hearts. Only someone who makes us feel loved for who we are can give peace to our hearts. The Holy Spirit, the love of God, does precisely that. He comes down within us; as the Spirit, he acts in our spirit. He comes down “within the heart”, as “the soul’s most welcome guest” (ibid). He is the very love of God, who does not abandon us; for being present to those who are alone is itself a source of comfort.

Dear sister, dear brother, if you feel the darkness of solitude, if you feel that an obstacle within you blocks the way to hope, if your heart has a festering wound, if you can see no way out, then open your heart to the Holy Spirit. Saint Bonaventure tells us that, “where the trials are greater, he brings greater comfort, not like the world, which comforts and flatters us when things go well, but derides and condemns us when they do not” (Homily in the Octave of the Ascension). That is what the world does, that is especially what the hostile spirit, the devil, does. First, he flatters us and makes us feel invincible (for the blandishments of the devil feed our vanity); then he flings us down and makes us feel that we are failures. He toys with us. He does everything to cast us down, whereas the Spirit of the risen Lord wants to raise us up. Look at the apostles: they were alone that morning, alone and bewildered, cowering behind closed doors, living in fear and overwhelmed by their weaknesses, failings and their sins, for they had denied Christ. The years they had spent with Jesus had not changed them: they were no different than they had been. Then, they received the Spirit and everything changed: the problems and failings remained, yet they were no longer afraid of them, nor of any who would be hostile to them. They sensed comfort within and they wanted to overflow with the comfort of God. Before, they were fearful; now their only fear was that of not testifying to the love they had received. Jesus had foretold this: “[The Spirit] will testify on my behalf; you also are to testify” (Jn 15:26-27).

Let us go another step. We too are called to testify in the Holy Spirit, to become paracletes, comforters. The Spirit is asking us to embody the comfort he brings. How can we do this? Not by making great speeches, but by drawing near to others. Not with trite words, but with prayer and closeness. Let us remember that closeness, compassion and tenderness are God’s “trademark”, always. The Paraclete is telling the Church that today is the time for comforting. It is more the time for joyfully proclaiming the Gospel than for combatting paganism. It is the time for bringing the joy of the Risen Lord, not for lamenting the drama of secularization. It is the time for pouring out love upon the world, yet not embracing worldliness. It is more the time for testifying to mercy, than for inculcating rules and regulations. It is the time of the Paraclete! It is the time of freedom of heart, in the Paraclete.

The Paraclete is also the Advocate.

In Jesus’ day, advocates did not do what they do today: rather than speaking in the place of defendants, they simply stood next to them and suggested arguments they could use in their own defence. That is what the Paraclete does, for he is “the spirit of truth” (v. 26). He does not take our place, but defends us from the deceits of evil by inspiring thoughts and feelings. He does so discreetly, without forcing us: he proposes but does not impose. The spirit of deceit, the evil one, does the opposite: he tries to force us; he wants to make us think that we must always yield to the allure and the promptings of vice. Let us try to accept three suggestions that are typical of the Paraclete, our Advocate. They are three fundamental antidotes to three temptations that today are so widespread.

The first advice offered by the Holy Spirit is, “Live in the present”. The present, not the past or the future. The Paraclete affirmsthe primacy of today, against the temptation to let ourselves be paralyzed by rancour or memories of the past, or by uncertainty or fear about the future. The Spirit reminds us of the grace of the present moment. There is no better time for us: now, here and now, is the one and only time to do good, to make our life a gift. Let us live in the present!

The Spirit also tells us, “Look to the whole”. The whole, not the part. The Spirit does not mould isolated individuals, but shapes us into a Church in the wide variety of our charisms, into a unity that is never uniformity. The Paraclete affirms the primacy of the whole. There, in the whole, in the community, the Spirit prefers to work and to bring newness. Let us look at the apostles. They were all quite different. They included, for example, Matthew, a tax collector who collaborated with the Romans, and Simon called the zealot, who fought them. They had contrary political ideas, different visions of the world. Yet once they received the Spirit, they learned to give primacy not to their human viewpoints but to the “whole” that is God’s plan. Today, if we listen to the Spirit, we will not be concerned with conservatives and progressives, traditionalists and innovators, right and left. When those become our criteria, then the Church has forgotten the Spirit. The Paraclete impels us to unity, to concord, to the harmony of diversity. He makes us see ourselves as parts of the same body, brothers and sisters of one another. Let us look to the whole! The enemy wants diversity to become opposition and so he makes them become ideologies. Say no to ideologies, yes to the whole.

The third advice of the Spirit is, “Put God before yourself”. This is the decisive step in the spiritual life, which is not the sum of our own merits and achievements, but a humble openness to God. The Spirit affirms the primacy of grace. Only by emptying ourselves, do we leave room for the Lord; only by giving ourselves to him, do we find ourselves; only by becoming poor in spirit, do we become rich in the Holy Spirit. This is also true of the Church. We save no one, not even ourselves, by our own efforts. If we give priority to our own projects, our structures, our plans for reform, we will be concerned only about effectiveness, efficiency, we will think only in horizontal terms and, as a result, we will bear no fruit. An “-ism” is an ideology that divides and separates. The Church is human, but it is not merely a human organization, it is the temple of the Holy Spirit. Jesus brought the fire of the Spirit to the earth and the Church is reformed by the anointing of grace, the gratuity of the anointing of grace, the power of prayer, the joy of mission and the disarming beauty of poverty. Let us put God in first place!

Holy Spirit, Paraclete Spirit, comfort our hearts. Make us missionaries of your comfort, paracletes of your mercy before the world. Our Advocate, sweet counsellor of the soul, make us witnesses of the “today” of God, prophets of unity for the Church and humanity, and apostles grounded in your grace, which creates and renews all things. Amen.
— Homily of his Holiness Pope Francis

The Catechism of the Catholic Church provides the following response:

“No one comprehends the thoughts of God except the Spirit of God.”  Now God’s Spirit, who reveals God, makes known to us Christ, his Word, his living Utterance, but the Spirit does not speak of himself.  The Spirit who “has spoken through the prophets” makes us hear the Father’s Word, but we do not hear the Spirit himself.  We know him only in the movement by which he reveals the Word to us and disposes us to welcome him in faith.  The Spirit of truth who “unveils” Christ to us “will not speak on his own.”  Such properly divine self-effacement explains why “the world cannot receive (him), because it neither sees him nor knows him,” while those who believe in Christ know the Spirit because he dwells with them.
— CCC, 2000, para. 687

The Church, a communion living in the faith of the apostles which she transmits, is the place where we know the Holy Spirit:

• in the Scriptures he inspired;
• in the Tradition, to which the Church Fathers are always timely witnesses;
• in the Church’s Magisterium, which he assists;
• in the sacramental liturgy, through its words and symbols, in which the Holy Spirit puts us into communion with Christ;
• in prayer, wherein he intercedes for us;
• in the charisms and ministries by which the Church is built up;
• in the signs of apostolic and missionary life;
• in the witness of saints through whom he manifests his holiness and continues the work of salvation.

–- CCC, 2000, para. 688

On the following pages, we will explore further the works, signs and symbols of the Holy Spirit and how His actions influence and affect our daily lives.