“…Christian marriage is an ecclesial state, like being a monk, a nun, or a priest (CCC 1631). It exists not only for the good of the spouses, but for the good of the whole Christian community.
Christian marriage is also different because it is a sacrament — a symbol of a supernatural reality, a symbol through which God promises to bestow His grace on us. What is being symbolized in the Christian sacrament of marriage is not romantic love or even the perfect love of the Blessed Trinity, but the sacrificial love of Jesus Christ’s suffering and death for the sake of His bride, the Church. Christ gave His life to bring His spouse to God.
Furthermore, the effect of the grace that is given through the sacrament of marriage is not to enable or to facilitate romantic love. God gives grace in the sacrament of marriage to enable the spouses to love sacrificially, to bear wrongs, to forgive offenses, to be chaste, to welcome and educate children, and perhaps even to die in the service of one’s family…
What does it even mean to say that a marriage is not “valid”? What on earth is “validity”? In a broad sense, something is valid if it works, if it brings about its intended effect. Philosophers speak of an argument being valid if its conclusion follows logically from its premises. In law, a valid contract is one that is legally binding. The celebration of a sacrament can also be understood as valid or invalid. In Catholic theology, a valid sacrament brings about its intended effect. An invalid sacrament (which is really no sacrament at all) does not.
Marriages, therefore, can be valid or invalid. In a valid marriage, the parties really do incur the duties and obligations of marriage and accrue its benefits, privileges, and rights. An invalid marriage is not really a marriage at all. The moral rights, duties, and benefits of marriage do not flow from it, and civil law, if it is to be just, ought not say otherwise.
The idea of validity is implicit in contemporary debates about so-called gay marriage. One side imagines that marriage is simply a right extended by the state that can be applied to any two (three? four?) people who want social privileges attached to their romantic relationships. By contrast, the defenders of tradition hold that marriage is something intrinsically and necessarily connected to our nature created as male and female. The state can no more convey the right to marry to same-sex couples than it can square the circle. Marriage is not just any kind of union. It is the kind of union naturally fulfilled in the procreation of children.26…
…New Catholics are often surprised to learn that the Church does not see it this way (Ed. that nothing else matters but their own will, their choice to get married civilly, at least, outside the Church]. Marriage is not simply a cultural construct that means whatever we want it to mean. It is not simply the desire for children or for intimacy that creates the conditions for marriage. Rather, marriage is something that derives from the natural law. When it comes to marriage, the Church does not arbitrarily create the conditions for validity. The conditions for a true and valid marriage flow from our nature created as male and female.27
The Church does not invent or impose those conditions. She merely recognizes them. It is not only to Catholics that She speaks, and it is not only about Christian marriage that She teaches. The Church has authority from Christ to judge all moral questions, including the validity of natural marriage.28 The Church discerns and teaches those moral norms that emerge not only from revelation but also from natural law.29
The case is a bit different with respect to Christian marriage. Christian marriage presupposes the conditions for a valid, natural marriage, i.e., one man and one woman united indissolubly for life for the good of the spouses and the bearing and raising of offspring. But Christian marriage is also an ecclesial state. It grants certain rights and privileges within the Church…
…It is important to be precise: To say that a sacrament is invalid does not mean that the persons involved have been denied all grace. God can always extend grace if He chooses. In fact, the prompting and nudging toward faith or holiness that Catholics call actual grace routinely occurs outside the sacraments, as Christ draws people to receive the grace of baptism. (Baptized people also receive actual graces.) But the habitual grace made available through the Christian sacrament of marriage cannot be presumed apart from a valid sacrament. An invalid marriage cannot give rise to sacramental grace.
-Anders, Dr. David. The Catholic Church Saved My Marriage: Discovering Hidden Grace in the Sacrament of Matrimony (p. 120-123). Sophia Institute Press. Kindle Edition.
26 Patrick Lee and Robert P. George, Conjugal Union: What Marriage Is and Why It Matters (Cambridge: Cambridge University Press, 2014), 47.
27 “The personal bond of marriage is established precisely at the natural level of the male or female mode of being a human person.” Pope St. John Paul II, “God Himself Is the Author of Marriage,” L’Osservatore Romano, English ed., February 7, 2001, 3, posted at EWTN, https://www.ewtn.com/library/PAPALDOC/JP2MATR.HTM.
28 See Code of Canon Law 747.2; Veritatis Splendor, no. 110.
29 Humanae Vitae, no. 4.