From the beginning until “the fullness of time,” The joint mission of the Father’s Word and Spirit remains hidden, but it is at work. God’s Spirit prepares for the time of the Messiah. Neither is fully revealed but both are already promised, to be watched for and welcomed at their manifestation. So, for this reason, when the Church reads the Old Testament, she searches there for what the Spirit, “who has spoken through the prophets,” wants to tell us about Christ.
By “prophets” the faith of the Church here understands all whom the Holy Spirit inspired in the composition of the sacred books, both of the Old and the New Testaments. Jewish tradition distinguishes first the Law (the five first books or Pentateuch), then the Prophets (our historical and prophetic books) and finally the Writings (especially the wisdom literature, in particular the Psalms).
The Word of God and his Breath are at the origin of the being and life of every creature:
It belongs to the Holy Spirit to rule, sanctify, and animate creation, for he is God, consubstantial with the Father and the Son…. Power over life pertains to the Spirit, for being God he preserves creation in the Father through the Son.
“God fashioned man with his own hands [that is, the Son and the Holy Spirit] and impressed his own form on the flesh he had fashioned, in such a way that even what was visible might bear the divine form.”
The Spirit of the promise
Disfigured by sin and death, man remains “in the image of God,” in the image of the Son, but is deprived “of the glory of God,” of his “likeness.” the promise made to Abraham inaugurates the economy of salvation, at the culmination of which the Son himself will assume that “image” and restore it in the Father’s “likeness” by giving it again its Glory, the Spirit who is “the giver of life.”
Against all human hope, God promises descendants to Abraham, as the fruit of faith and of the power of the Holy Spirit. In Abraham’s progeny all the nations of the earth will be blessed. This progeny will be Christ himself, in whom the outpouring of the Holy Spirit will “gather into one the children of God who are scattered abroad.” God commits himself by his own solemn oath to giving his beloved Son and “the promised Holy Spirit . . . [who is] the guarantee of our inheritance until we acquire possession of it.”
From the Catechism of the Church 702-706