From Pope St. John Paul II’s Apostolic Exhortation Familiaris Consortio (1981):
Precisely because in the celebration of the sacrament very special attention must be devoted to the moral and spiritual dispositions of those being married, in particular to their faith, we must here deal with a not infrequent difficulty in which the pastors of the Church can find themselves in the context of our secularized society.
In fact, the faith of the person asking the Church for marriage can exist in different degrees, and it is the primary duty of pastors to bring about a rediscovery of this faith and to nourish it and bring it to maturity. But pastors must also understand the reasons that lead the Church also to admit to the celebration of marriage those who are imperfectly disposed.
The sacrament of Matrimony has this specific element that distinguishes it from all the other sacraments: it is the sacrament of something that was part of the very economy of creation; it is the very conjugal covenant instituted by the Creator “in the beginning.” Therefore the decision of a man and a woman to marry in accordance with this divine plan, that is to say, the decision to commit by their irrevocable conjugal consent their whole lives in indissoluble love and unconditional fidelity, really involves, even if not in a fully conscious way, an attitude of profound obedience to the will of God, an attitude which cannot exist without God’s grace. They have thus already begun what is in a true and proper sense a journey towards salvation, a journey which the celebration of the sacrament and the immediate preparation for it can complement and bring to completion, given the uprightness of their intention.
On the other hand it is true that in some places engaged couples ask to be married in church for motives which are social rather than genuinely religious. This is not surprising. Marriage, in fact, is not an event that concerns only the persons actually getting married. By its very nature it is also a social matter, committing the couple being married in the eyes of society. And its celebration has always been an occasion of rejoicing that brings together families and friends. It therefore goes without saying that social as well as personal motives enter into the request to be married in church.
Nevertheless, it must not be forgotten that these engaged couples, by virtue of their Baptism, are already really sharers in Christ’s marriage Covenant with the Church, and that, by their right intention, they have accepted God’s plan regarding marriage and therefore at least implicitly consent to what the Church intends to do when she celebrates marriage. Thus, the fact that motives of a social nature also enter into the request is not enough to justify refusal on the part of pastors. Moreover, as the Second Vatican Council teaches, the sacraments by words and ritual elements nourish and strengthen faith”:168 that faith towards which the married couple are already journeying by reason of the uprightness of their intention, which Christ’s grace certainly does not fail to favor and support.
As for wishing to lay down further criteria for admission to the ecclesial celebration of marriage, criteria that would concern the level of faith of those to be married, this would above all involve grave risks. In the first place, the risk of making unfounded and discriminatory judgments; secondly, the risk of causing doubts about the validity of marriages already celebrated, with grave harm to Christian communities, and new and unjustified anxieties to the consciences of married couples; one would also fall into the danger of calling into question the sacramental nature of many marriages of brethren separated from full communion with the Catholic Church, thus contradicting ecclesial tradition.
However, when in spite of all efforts, engaged couples show that they reject explicitly and formally what the Church intends to do when the marriage of baptized persons is celebrated, the pastor of souls cannot admit them to the celebration of marriage. In spite of his reluctance to do so, he has the duty to take note of the situation and to make it clear to those concerned that, in these circumstances, it is not the Church that is placing an obstacle in the way of the celebration that they are asking for, but themselves.
Once more there appears in all its urgency the need for evangelization and catechesis before and after marriage, effected by the whole Christian community, so that every man and woman that gets married celebrates the sacrament of Matrimony not only validly but also fruitfully.
168 Sacrosanctum Concilium, 59.
— Familiaris Consortio 68