Vatican Council II On the Church, 4
"When the work which the Father had given the Son to do on
earth was accomplished, the Holy Spirit was sent on the day
of Pentecost in order that He might forever sanctify the Church.
All believers have access to the Father through Christ in the
one Spirit (Eph 2:18). He is the Spirit of life, a fountain of
water springing up to life eternal (Jn 4:14; 7:38-39). Through
him the Father gives life to men who are dead from sin, till at
last he revives in Christ even their mortal bodies (Rom 8:10-11).
The Spirit dwells in the Church and in the hearts of the faithful
as in a temple (1 Cor 3:16; 6:19). In them he prays and bears
witness to the fact that they are adopted sons (Gal 4:6;
Rom 8:15-16, 26). "
Vatican II -- book cover