Catechism of the Catholic Church

796 The unity of Christ and the Church, head and members of one Body, also implies the distinction of the two within a personal relationship. This aspect is often expressed by the image of bridegroom and bride. The theme of Christ as Bridegroom of the Church was prepared for by the prophets and announced by John the Baptist. ²³⁴ The Lord referred to himself as the "bridegroom." ²³⁵ The Apostle speaks of the whole Church and of each of the faithful, members of his Body, as a bride "betrothed" to Christ the Lord so as to become but one spirit with him. ²³⁶ The Church is the spotless bride of the spotless Lamb. ²³⁷ "Christ loved the Church and gave himself up for her, that he might sanctify her." ²³⁸ He has joined her with himself in an everlasting covenant and never stops caring for her as for his own body: ²³⁹

This is the whole Christ, head and body, one formed from many . . . whether the head or members speak, it is Christ who speaks. He speaks in his role as the head (ex persona capitis) and in his role as body (ex persona corporis). What does this mean? "The two will become one flesh. This is a great mystery, and I am applying it to Christ and the Church." ²⁴⁰ And the Lord himself says in the Gospel: "So they are no longer two, but one flesh." ²⁴¹ They are, in fact, two different persons, yet they are one in the conjugal union, . . . as head, he calls himself the bridegroom, as body, he calls himself "bride." ²⁴²