Sacred Scripture begins with the creation of man and woman in the image and likeness of God, and concludes with a vision of the "wedding feast of the Lamb" (Revelation 19:7). St Paul said: "Husbands, love your wives, as Christ loved the Church... This is a great mystery, and I mean in reference to Christ and the Church" (Ephesian 5:25-32).
The marriage covenant, by which a man and a woman form with each other an intimate communion of of life and love, has been founded by the Creator. By its very nature it is ordered to the good of the couple, as well as to the generation and education of children. Christ the Lord raised marriage between the baptized to the dignity of a Sacrament.
The Sacrament of Matrimony signifies the union of Christ and the Church. It gives spouses the grace to love each other with the love with which Christ loves the Church. This grace thus perfects the human love of the spouses, strengthens their indissoluble unity, and sanctifies them on the way to eternal life.
Marriage is based on the consent of the contracting parties, that is, on their will to give themselves, each to the ogher, mutually and definitively, in order to live a covenant of faithful and truitful love.
Since marriage establishes the coupld in a public state of life in the DHurch, it is fitting that its celebration be public, in a liturgical celebration, before the priest or deacon, the witnesses, and the assembly of the faithful.
Unity, indissolubility, and openness to fertility are essential to marriage. Divorce separates what God has joined; the refusal of fertility turns married life away from its "supreme gift," the child. The remarriage of persons divorced from a living, lawful spouse contravenes the plan and law of God as taught by Christ. They are not separated from the Church, but they cannot receive Eucharistic communion. They will lead Christian lives especially by educating their children in the faigh.
The Christian home is where children receive the first proclamation of the faith. For this reason the family home is rightly called "the domestic church," a community of grace and prayer, a school of human virtues and of Christian charity.
To learn more, see Genesis 1:26-31, Paul's Letter to the Ephesians 5:21-32, and The Catechism of the Catholic Church, paragraphs 1601-1666.