Vatican II, "Gaudium et spes"
A man and a woman, who by the marriage covenant of conjugal love ‘are no longer two, but one flesh’, render mutual help and service to each other through an intimate union of their persons and of their actions.
Through this union they experience the meaning of their oneness and attain to it with growing perfection day by day. As a mutual gift of two persons, this intimate union, as well as the good of the children, imposes total fidelity on the spouses and argues for an unbreakable oneness between them.
Christ the Lord abundantly blessed this many-faceted love, welling up as it does from the fountain of divine love and structured as it is on the model of his union with the Church.
As God of old made himself present to his people through a covenant of love and fidelity, so now the Saviour of men and the spouse of the Church comes into the lives of married Christians through the sacrament of matrimony. He abides with them thereafter so that, just as he loved the Church and handed himself over on her behalf, the spouses may love each other with perpetual fidelity through mutual self-bestowal.
Authentic married love is caught up into divine love and is governed and enriched by Christ’s redeeming power and the saving activity of the Church. Thus this love can lead the spouses to God with powerful effect and can aid and strengthen them in the sublime office of being a father or a mother.
For this reason, Christian spouses have a special sacrament by which they are fortified and receive a kind of consecration in the duties and dignity of their state. By virtue of this sacrament, as spouses fulfil their conjugal and family obligations, they are penetrated with the spirit of Christ. This spirit suffuses their whole lives with faith, hope, and charity. Thus they increasingly advance their own perfection, as well as their mutual sanctification, and hence contribute jointly to the glory of God.
As a result, with their parents leading the way by example and family prayer, children and indeed everyone gathered around the family hearth will find a readier path to human maturity, salvation, and holiness. Graced with the dignity and office of fatherhood and motherhood, parents will energetically acquit themselves of a duty which devolves primarily on them, namely education, and especially religious education.
As living members of the family, children contribute in their own way to making their parents holy. For they will respond to the kindness of their parents with sentiments of gratitude, with love and trust. They will stand by them as children should when hardships overtake their parents and old age brings its loneliness.