What is meant by the expression "sensus fidei"?
This expression is not properly speaking theological, nor is it consequently precisely defined. However, it is used to mean a "way of thinking that is governed by the truths of the Faith." It is in this sense that it is used, for example, by Archbishop Lefebvre, when speaking of the Novus Ordo Missae and how it is rejected as by a kind of supernatural instinct by those who still think as the Church has always thought, governed by the principles of the Faith. Allow me to quote the following text, written by Archbishop Lefebvre for the Cor Unum newsletter on February 16, 1980 (§269):
We had always said that we consider the Novus Ordo Missae to be dangerous for the faith of both priests and faithful, and that, consequently, it was inconceivable to group and form young aspirants to the priesthood around this new altar. The facts prove us to be right. The sensus fidei of the faithful, there where it is not yet corrupt, gives us total approval.
Understood in this sense, the "spirit of the Faith" is directly analogous to St. Ignatius's Rules for Thinking with the Church. These 18 rules contained in the book of the exercises of St. Ignatius of Loyola are a treasure, a summary of the attitudes, convictions, way of thinking that characterize the profoundly supernatural man, who is penetrated by the principles of the Faith. They describe perfectly well the sense of the Faith, as being a spirit of submission to the Church's judgment and way of thinking, and include such things as the praising of frequent sacramental Confession and Holy Communion, the frequent assistance at Mass, the recitation of long prayers and the Divine Office, the religious life and its three vows, the relics of the saints and their veneration, the precepts of the Church and acts of exterior and interior penance, the veneration of sacred images and so on.
It follows from this that a person can have the Faith, without the "spirit of the Faith." For the Catholic Faith itself is destroyed only by formal heresy, the pertinacious denial of a revealed dogma. However, the spirit of the Faith is lost by any way of thinking that is contrary to the Church's way of thinking, that does not take into account divine revelation and supernatural Truth. This is particularly the case of the modernists and those who promote the New Mass. They are not, in general, heretics, and are careful not to deny a defined dogma of Faith. However, little by little the assistance at the New Mass undermines the convictions of Faith that ought to govern the lives and in particular the prayers of Catholics. They become humanistic, man-centered, directed towards personal experience, rather than towards the salvation of the soul and the greater honor and glory of God. It was for this reason that St. Pius X condemned the Sillon movement in 1910. He did not say that it was heretical, but rather that "judging the words and deeds, we feel compelled to say that in this action as well as in its doctrine, the Sillon does not give satisfaction to the Church" (§30). Archbishop Lefebvre comments on this observation that the spirit of the Sillon was not the spirit of the Church:
In the same way, when he (St. Pius X) says that Modernism is the synthesis of all the heresies, he does not add that all those favorable to Modernism are heretics. He only says that it is the synthesis of all the heresies in its doctrine. (Against the Heresies, p. 281)
However, that the various manifestations of modernism, whether it be the New Mass, whether it be Ecumenism, whether it be secularism, indifferentism or religious liberty, demonstrate clearly the loss of the spirit of the Faith. This is well described by Romano Amerio:
For the new theology, it is not stability that characterizes real faith, but rather the mobility of an endless searching. People even go so far as to say that an authentic faith must go into crisis....This dynamic view of faith is immediately derived from modernism, which holds that faith is procured by a feeling for the divine, and that conceptual truths that the intellect produces are merely changeable expressions of that feeling....The mistake in this position lies in regarding as humble an attitude that is really an intense form of pride....In short the Object is being valued less than the subject and an anthropocentric view is being adopted that is irreconcilable with religion.... (Iota Unum, p. 375)
In this way the spirit of the Faith, the objective submission of the intellect to divinely revealed Truth, is destroyed.
The importance of this spirit of the Faith in present day Catholics can, consequently, escape no one. Without it, we will fall to the novelties of the post-conciliar church. In another of his newsletters (June 26, 1982) Archbishop Lefebvre pointed out that the spirit of Faith is identical with the spirit of the Church: "The spirit of the Society is the spirit of the Church, the spirit of faith in Our Lord Jesus Christ and His redemptive work." He goes on to explain that this spirit of faith is the fruit of prayer, by which the Faith penetrates into our souls:
This spirit of faith is essentially a spirit contemplating the crucified and glorified Jesus. The faith is the seed of the beatific vision, which is an eternally blessed contemplation.
He further points out that the spirit of faith is to be found where the life of the Church is to be found:
If the teaching that is contained in the liturgical life is so admirable and draws us towards an ever greater sanctification of soul, then the practical directives of the Church throughout its history, as well as its approval of the many foundations destined to sanctify soul, not to mention the examples of the saints, are all equally precious guidelines for our souls. In following them, according to the grace God grants us, we can be sure of not deceiving ourselves. Contemplation, obedience and humility are all the elements of one sole reality: the imitation of Jesus Christ and participation in His infinite love.
This passage holds the key to understanding whether or not we have the spirit of Faith. The love of the Church's traditional spiritual teachings, and saints, and the longing for contemplation, obedience and humility are the sign that we are truly seeking the spirit of Faith. For it really is the fruit of the gift of the Holy Ghost that we call the gift of Understanding, through which we penetrate into the depth of supernatural truths and unveil their secrets. This is well explained by Archbishop Martinez:
It is the gift of understanding given to every Christian which makes him apprehend supernatural truths when this is necessary for the attainment of his salvation. And as it increases, this gift produces things even more wonderful in our soul; it makes us penetrate into the very mysteries of religion; by it we understand the beautiful harmonies in spiritual things. (The Sanctifier, p. 183)