MARRIAGE. As a natural institution, the lasting union of a man and a woman who agree to give and receive rights over each other for the performance of the act of generation and for the fostering of their mutual love.
The state of marriage implies four chief conditions: 1. there must be a union of opposite sexes; it is therefore opposed to all forms of unnatural, homosexual behavior; 2. it is a permanent union until the death of either spouse; 3. it is an exclusive union, so that extramarital acts are a violation of justice; and 4. its permanence and exclusiveness are guaranteed by contract; mere living together, without mutually binding themselves to do so, is concubinage and not marriage.
Christ elevated marriage to a sacrament of the New Law. Christian spouses signify and partake of the mystery of that unity and fruitful love which exists between Christ and his Church, helping each other attain to holiness in their married life and in the rearing and education of their children.