Catechism of the Catholic Church

"The Church... is held, as a matter of faith, to be unfailingly holy. This is because Christ, the Son of God, who with the Father and the Spirit is hailed as alone holy,' loved the Church as his Bride, giving himself up for her so as to sanctify her; he joined her to himself as his body and endowed her with the gift of the Holy Spirit for the glory of God." The Church, then, is "the holy People of God," and her members are called "saints." (459, 796, 946)