“In 1930, the Anglican Church’s Lambeth Conference resulted in a statement that made a seismic shift in Christian thinking and practice by opening the door to allowing contraception and allowing remarriage after divorce. Pope Pius XII knew this required a response to let the world know that the Catholic Church had not and would not follow suit. The result was Casti Connubii, a wise and beautiful encyclical letter about Christian marriage.
The pope reaffirmed the Church’s opposition to divorce and to birth control, but he also acknowledged that these standards are difficult. The Holy Father did not offer an easy solution; on the contrary, he freely admitted that many Catholics find them impossible. The fault, however, does not lie with God but with us. Pius cited the Council of Trent, which teaches that God never demands the impossible of us: He always supplies the necessary grace.
If God supplies the grace, then why do some Catholics find the moral demands of marriage to be impossible? The pope’s answer is astonishing for its realism and honesty. They find it impossible, he says, because they do not cooperate with grace. They do not live the faith generously. They are unwilling to sacrifice. If they do not do everything in their power — if they select only those parts of the Faith they like, or if they do not give themselves to prayer and the sacraments — then the grace of matrimony will be an unused talent hidden in the field (see Matt. 25:14–30). The pope explains:
Nevertheless, since it is a law of divine Providence in the supernatural order that men do not reap the full fruit of the Sacraments which they receive after acquiring the use of reason unless they cooperate with grace, the grace of matrimony will remain for the most part an unused talent hidden in the field unless the parties exercise these supernatural powers and cultivate and develop the seeds of grace they have received. If, however, doing all that lies with their power, they cooperate diligently, they will be able with ease to bear the burdens of their state and to fulfill their duties. By such a sacrament they will be strengthened, sanctified and in a manner consecrated.39
Catholics who reject Church teaching and do not vigorously practice their Faith simply should not expect grace from the sacrament. It may sound harsh, but they should not be surprised if their marriages fail. On the other hand, Catholics who believe the Church and practice their Faith can be confident that God will supply the necessary grace.
What is necessary in order to cooperate with the grace offered in the sacrament of matrimony? This is something that Pope John Paul II wrote about extensively. In his apostolic exhortation Familiaris Consortio, he explains that couples must accept and follow Church teaching on human sexuality, prayer, and the sacraments. He writes:
There is no doubt that these conditions [for receiving the grace] must include persistence and patience, humility and strength of mind, filial trust in God and in His grace, and frequent recourse to prayer and to the sacraments of the Eucharist and of Reconciliation. Thus strengthened, Christian husbands and wives will be able to keep alive their awareness of the unique influence that the grace of the sacrament of marriage has on every aspect of married life, including therefore their sexuality: the gift of the Spirit, accepted and responded to by husband and wife, helps them to live their human sexuality in accordance with God’s plan and as a sign of the unitive and fruitful love of Christ for His Church. (33)
…Married love does not exist for the purpose of romantic gratification. Married love exists “to lead the spouses to God” and to strengthen them in the “sublime office of being a mother or a father.”40
Anders, Dr. David. The Catholic Church Saved My Marriage: Discovering Hidden Grace in the Sacrament of Matrimony (p. 160-161). Sophia Institute Press. Kindle Edition.
33 Augustine, On Christian Doctrine, trans. D. W. Robertson (New York: Macmillan, 1958), 65.
39 Casti Connubii, no. 41.
40 Gaudium et Spes, no. 48.