The Holy Spirit, who with the Father and the Son, created the universe, who guided the People of Israel through history and spoke through the Prophets, who in the fullness of time cooperated in our redemption, came down at Pentecost upon the nascent Church and made her missionary, sending her out to proclaim to all peoples the victory of divine love over sin and death.
The Holy Spirit is the soul of the Church. Without him what would she be reduced to? She would certainly be an important movement in history, a complex and solid social institution, perhaps a sort of humanitarian agency. And to tell the truth she is considered such by those who do not see her from a perspective of faith. Yet, the reality is that in her true nature and also in her authentic presence in history, the Church is ceaselessly formed and guided by the Spirit of her Lord. She is a living body, whose vitality is, precisely, the fruit of the invisible divine Spirit.
Pope Benedict XVI
Regina Caeli on May 31, 2009
The Solemnity of Pentecost