From Pope St. John Paul II’s Apostolic Exhortation Familiaris Consortio (1981):
But it is especially necessary to recognize the unique place that, in this field, belongs to the mission of married couples and Christian families, by virtue of the grace received in the sacrament. This mission must be placed at the service of the building up of the Church, the establishing of the Kingdom of God in history. This is demanded as an act of docile obedience to Christ the Lord. For it is He who, by virtue of the fact that marriage of baptized persons has been raised to a sacrament, confers upon Christian married couples a special mission as apostles, sending them as workers into His vineyard, and, in a very special way, into this field of the family.
In this activity, married couples act in communion and collaboration with the other members of the Church, who also work for the family, contributing their own gifts and ministries. This apostolate will be exercised in the first place within the families of those concerned, through the witness of a life lived in conformity with the divine law in all its aspects, through the Christian formation of the children, through helping them to mature in faith, through education to chastity, through preparation for life, through vigilance in protecting them from the ideological and moral dangers with which they are often threatened, through their gradual and responsible inclusion in the ecclesial community and the civil community, through help and advice in choosing a vocation, through mutual help among family members for human and Christian growth together, and so on. The apostolate of the family will also become wider through works of spiritual and material charity towards other families, especially those most in need of help and support, towards the poor, the sick, the old, the handicapped, orphans, widows, spouses that have been abandoned, unmarried mothers and mothers-to-be in difficult situations who are tempted to have recourse to abortion, and so on.
— Familiaris Consortio 71