43 The Church "becomes herself a mother by accepting God's word with fidelity." Like Mary, who first believed by accepting the word of God revealed to her at the Annunciation and by remaining faithful to that word in all her trials even unto the Cross, so too the Church becomes a mother when, accepting with fidelity the word of God, "by her preaching and by baptism she brings forth to a new and immortal life children who are conceived of the Holy Spirit and born of God." This "maternal" characteristic of the Church was expressed in a particularly vivid way by the Apostle to the Gentiles when he wrote: "My little children, with whom I am again in travail until Christ be formed in you!" (Gal. 4:19) These words of Saint Paul contain an interesting sign of the early Church's awareness of her own motherhood, linked to her apostolic service to mankind. This awareness enabled and still enables the Church to see the mystery of her life and mission modelled upon the example of the Mother of the Son, who is "the first-born among many brethren" (Rom. 8:29). It can be said that from Mary the Church also learns her own motherhood: she recognizes the maternal dimension of her vocation, which is essentially bound to her sacramental nature, in "contemplating Mary's mysterious sanctity, imitating her charity and faithfully fulfilling the Father's will." If the Church is the sign and instrument of intimate union with God, she is so by reason of her motherhood, because, receiving life from the Spirit, she "generates" sons and daughters of the human race to a new life in Christ. For, just as Mary is at the service of the mystery of the Incarnation, so the Church is always at the service of the mystery of adoption to sonship through grace. Likewise, following the example of Mary, the Church remains the virgin faithful to her spouse: The Church herself is a virgin who keeps whole and pure the fidelity she has pledged to her Spouse." For the Church is the spouse of Christ, as is clear from the Pauline Letters (cf. Eph. 5:21-33; 2 Cor. 11:2), and from the title found in John: "bride of the Lamb" (Rev. 21:9). If the Church as spouse "keeps the fidelity she has pledged to Christ," this fidelity, even though in the Apostle's teaching it has become an image of marriage (cf. Eph. 5:23-33), also has value as a model of total self-giving to God in celibacy "for the kingdom of heaven," in virginity consecrated to God (cf. Mt. 19:11-12; 2 Cor. 11:2). Precisely such virginity, after the example of the Virgin of Nazareth, is the source of a special spiritual fruitfulness: it is the source of motherhood in the Holy Spirit. But the Church also preserves the faith received from Christ. Following the example of Mary, who kept and pondered in her heart everything relating to her divine Son (cf. Lk. 2:19, 51), the Church is committed to preserving the word of God and investigating its riches with discernment and prudence, in order to bear faithful witness to it before all mankind in every age.
Source: Redemptoris Mater (Vatican.va)