The sacrament of marriage is a visible sign of God's love for the Church. When a man and a woman are married in the Church, they receive the grace needed for a lifelong bond of unity.
Marriage is a Covenant
The Sacrament of Marriage is a covenantal union in the image of the covenants between God and his people with Abraham and later with Moses at Mt. Sinai. This divine covenant can never be broken. In this way, marriage is a union that bonds spouses together during their entire lifetime.
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 has loved his Church; the grace of the sacrament thus perfects the human love of the spouses, strengthens their indissoluble unity, and sanctifies them on the way to eternal life. (CCC 1661)
The love in a married relationship is exemplified in the total gift of one's self to another. It's this self-giving and self-sacrificing love that we see in our other model of marriage, the relationship between Christ and the Church.
Marriage is based on the consent of the contracting parties, Chat is, on their will to give themselves, each to the other, mutually and definitively, in order to live a covenant of faithful and fruitful love.(CCC 1662j
The Church takes the lifelong nature of the Sacrament of Marriage seriously. The Church teaches that a break in this covenant teaches goes against the natural law of God:
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 faith. (CCC 1665)
Marriage Reflects the Holy Trinity
We believe that God exists in eternal communion. Together, Father, Son and Holy Spirit are united in one being with no beginning and no end. Human beings, likewise, were created by God in God's image for the purpose of communion with another human being.
The Catechism of the Catholic Church states, "The Christian family is a communion of persons, a sign and image of the communion of the Father and the Son in the Holy Spirit" (CCC 2205). The Sacrament of Marriage is "unitive, indissoluble and calls us to be completely open to fertility." Christian marriage at its finest is a reflection of God's self-giving love expressed between the love of two people.