Holding to the propositions of revelation with doubt = opinion
Assenting to the propositions of revelation without doubt = faith
Sometimes I see it suggested that it is OK to doubt, or that doubt makes our faith healthier and more authentic. I agree that a tested faith is more mature, but a tested faith means we have maintained unconditional assent in spite of the attacks of doubt.
I sympathize with people's struggles, but I think it's important to understand that faith means giving unconditional assent to the articles of faith, and if assent is not unconditional then it is not assent and it is not faith. Doubt is a temptation, and we must never consent to it. I think of St. Therese of Lisieux, or St. Padre Pio, or Bl. Teresa of Calcutta, who were attacked by doubt but did not consent to it and maintained unconditional assent. They are examples of heroic faith.
Practicing the virtue of faith is like practicing the virtue of purity. Some thoughts may enter our head without our consent, but we do not lose the virtue as long as we fully resist the thoughts and do not consent to them.
I worry that the virtue of faith is not fully taught and preached, which is upsetting because faith is necessary for salvation.
I have gathered some references for discussion.
Catechism of the Council of Trent:
That faith thus understood is necessary to salvation no man can reasonably doubt, particularly since it is written: Without faith it is impossible to please God. For as the end proposed to man as his ultimate happiness is far above the reach of human understanding, it was therefore necessary that it should be made known to him by God. This knowledge, however, is nothing else than
faith, by which we yield our unhesitating assent to whatever the authority of our Holy Mother the Church teaches us to have been revealed by God; for the faithful cannot doubt those things of which God, who is truth itself, is the author. Hence we see the great difference that exists between this faith which we give to God and that which we yield to the writers of human history.
http://www.catholicapologetics.info/thechurch/catechism/ApostlesCreed00.shtml
Catechism of the Catholic Church:
Faith is
certain. It is more certain than all human knowledge because it is founded on the very word of God who cannot lie. To be sure, revealed truths can seem obscure to human reason and experience, but "the certainty that the divine light gives is greater than that which the light of natural reason gives." "
Ten thousand difficulties do not make one doubt."
157,
http://www.vatican.va/archive/ccc_css/archive/catechism/p1s1c3a1.htm
St. Thomas Aquinas:
Faith implies assent of the intellect to that which is believed. Now the intellect assents to a thing in two ways. First, through being moved to assent by its very object, which is known either by itself (as in the case of first principles, which are held by the habit of understanding), or through something else already known (as in the case of conclusions which are held by the habit of science). Secondly the intellect assents to something, not through being sufficiently moved to this assent by its proper object, but through an act of choice, whereby it turns voluntarily to one side rather than to the other:
and if this be accompanied by doubt or fear of the opposite side, there will be opinion, while, if there be certainty and no fear of the other side, there will be faith.
ST, "Faith," Article 2
http://www.newadvent.org/summa/3001.htm#article2
Bl. John H. Newman's three modes of holding a proposition:
And in fact, these three modes of entertaining propositions,—doubting them, inferring them, assenting to them, are so distinct in their action, that, when they are severally carried out into the intellectual habits of an individual, they become the principles and notes of three distinct states or characters of mind. For instance, in the case of Revealed Religion, according as one or other of these is paramount within him, a man is a sceptic as regards it; or a philosopher, thinking it more or less probable considered as a conclusion of reason; or he has an unhesitating faith in it, and is recognized as a believer. If he simply disbelieves, or dissents, then he is assenting to the contradictory of the thesis, viz. to the proposition that there is no Revelation.
Many minds of course there are, which are not under the predominant influence of any one of the three. Thus men are to be found of irreflective, impulsive, unsettled, or again of acute minds, who do not know what they believe and what they do not, and who may be by turns sceptics, inquirers, or believers; who doubt, assent, infer, and doubt again, according to the circumstances of the season. Nay further, in all minds there is a certain coexistence of these distinct acts; that is, of two of them, for we can at once infer and assent, though we cannot at once either assent or infer and also doubt. Indeed, in a multitude of cases we infer truths, or apparent truths, before, and while, and after we assent to them.
[...]
Assent is unconditional; else, it is not really represented by assertion. Inference is conditional, because a conclusion at least implies the assumption of premises, and still more, because in concrete matter, on which I am engaged, demonstration is impossible.
http://www.newmanreader.org/works/grammar/chapter1.html
Bl. Newman again:
I must insist upon this: faith implies a confidence in a man’s mind, that the thing believed is really true; but, if it is once true it never can be false. If it is true that God became man, what is the meaning of my anticipating a time when perhaps I shall not believe that God became man? This is nothing short of anticipating a time when I shall disbelieve a truth. And if I bargain to be allowed in time to come not to believe, or to doubt, that God became man, I am but asking to be allowed to doubt or disbelieve what I hold to be an eternal truth. I do not see the privilege in such a permission at all, or the meaning of wishing to secure it. If at present I have no doubt whatever about it, then I am but asking leave to fall into error; if at present I have doubts about it, then I do not believe it at present, that is, I have not faith. . . . I may love by halves, I may obey by halves; I cannot believe by halves: either I have faith, or I have it not.
http://newmanreader.org/works/discourses/index.html