"The matrimonial covenant, by which a man and a woman establish between themselves a partnership of the whole of life, is by its nature ordered toward the good of the spouses and the procreation and education of offspring; this covenant between baptized persons has been raised by Christ the Lord to the dignity of a sacrament" (CCC 1601).
Like the whole Church, every Christian family rests on a firm foundation, namely, Christ’s promise to be faithful to those he has chosen. When a man and a woman pledge themselves to each other in the sacrament of matrimony, they join in Christ’s promise and become a living sign of his union with the Church. (Eph 5:32)
Therefore, a committed, permanent, faithful relationship of husband and wife is the root of a family. It strengthens all the members, provides best for the needs of children, and causes the Church of the Home to be an effective sign of Christ in the world.
Follow the Way of Love, A pastoral message of the U.S. Catholic bishops to families.