God, the Holy Spirit
If God the Father is the Creator; and God the Son, the Redeemer; then God the Holy Spirit is called the Sanctifier, which is to say that he works in the midst of believers as an interior force guiding them along the path toward the Kingdom of Heaven.
In the Old Testament, the word "Spirit" — Hebrew word "ruah", meaning breath, wind or soul — is mentioned nearly 400 times. At times, he is in the blowing wind that God stirs; at other times, in the breath of life of humankind; or still again, in the breath issuing from the mouth of God.
In the New Testament, the Spirit operates in and through the person of Jesus. He is also called the Paraclete — meaning defence advocate — the Defender or the Spirit of Truth.
Whatever the designation given to the Holy Spirit, the Spirit always reveals the mysterious side of a reality that is difficult to define or to portray. Only certain images, such as the dove, fire, wind and a few other representations, are capable of expressing aspects of his unique way of working. It is said that the Holy Spirit is like the wind: it is not visible, nevertheless we perceive its effects on our skin, in the rustling leaves of a tree, in the swaying tall grass...
The Creed mentions the Holy Spirit and then lists a series of truths that are signs of his presence in the world. The Church — from the Latin "ecclesia" — was born of the Holy Spirit at Pentecost. It is the community of believers who, by and through the Spirit, gather around the Lord. The communion of saints is also the work of the Holy Spirit, who unites in love everyone who belongs to Christ in this world and the next. The Resurrection, which introduces us to eternal life, is also the fruit of the power of the Holy Spirit at work in Christians’ faith.
Jesus said: "And I will ask the Father, and he will give you another Advocate to be with you forever. This is the Spirit of truth, whom the world cannot receive, because it neither sees him nor knows him. You know him, because he abides with you, and he will be in you." (Jn 14: 16-17)