The Holy Spirit
The Holy Spirit is the third Person of the Trinity. He proceeds from the Father and the Son as the love that unites them, and he is fully God, equal and coeternal with the Father and the Son. He is the Lord acting in the heart of men: “The Lord is the Spirit; and where the Spirit of the Lord is, there is freedom.” 2 Corinthians 3:17
Lord who gives life
The Holy Spirit is the source of life. Present from the beginning over creation, he also bears in man the new life of God, the life that Christ communicates to his own: “It is the Spirit who gives life.” John 6:63 The Creed confesses him as Lord on the same level as the Father and the Son, and giver of all life.
He has spoken through the prophets
The Holy Spirit inspired the authors of the Scriptures and made the prophets speak in the name of God. It is he who, through the centuries, prepared the people to receive Christ and who makes the words of God living: “Borne by the Holy Spirit, men spoke on behalf of God.” 2 Peter 1:21
Poured out at Pentecost
Christ had promised the Spirit to his disciples. On the day of Pentecost, fifty days after Easter, the Holy Spirit descends upon them and gives birth to the Church in the world: “They were all filled with the Holy Spirit.” Acts 2:4
Since that day, the Spirit dwells in the Church, leads her into the truth and keeps her faithful to the teaching of Christ: “When he comes, the Spirit of truth, he will guide you into all the truth.” John 16:13
Present in the soul
The Holy Spirit dwells in the soul of the baptised through sanctifying grace. He pours into it the love of God, gives the virtues of faith, hope and charity, and makes the believer grow in holiness: “The love of God has been poured into our hearts through the Holy Spirit who has been given to us.” Romans 5:5
He also sustains prayer, to the point of praying within man when he no longer knows what to say: “The Spirit himself intercedes for us with sighs too deep for words.” Romans 8:26