In Brief CCC 867
© Libreria Editrice Vaticana Source: vatican.va
The Church is holy: the Most Holy God is her author; Christ, her bridegroom, gave himself up to make her holy; the Spirit of holiness gives her life. Since she still includes sinners, she is "the sinless one made up of sinners." Her holiness shines in the saints; in Mary she is already all-holy.
Read the full chapter 3. I Believe in the Holy Spirit ¶683–1065