Chapter 11 — Part I — Article IX (Of the Church)
Section 268. Q. Why is the Church holy? A. Because she is sanctified by Jesus Christ through his passion, through his doctrine, through his prayer, and through the Sacraments. Christ loved the Church, and gave himself for it; that he might sanctify it, having cleansed it with the washing of water by the Word, that he might present it to himself a glorious Church, not having spot, or wrinkle, or any such thing, but that it should be holy, and without blemish. Eph. v. 25-27. In his prayer to God the Father for believers, Jesus Christ said among other things: Sanctify them through thy truth: thy Word is truth. And for their sakes I sanctify myself, that they also may be sanctified in truth. John xvii.17, 19.