Ever since the age of Descartes, doubt has become fashionable. When Descartes introduced methodical doubt as a means to certainty, the intentional exercise of doubt has been the hallmark of the sophisticated. From the philosophes of the Enlightenment who adopted a position of radical skepticism towards the possibility of divine revelation, to the modern scientific establishment that doubts even the rationality of the human mind, doubt has become the disposition through which modern man views reality. Doubt has become such a prevalent part of the modern mindset that it has seeped into Christian thought, which has tended to baptize doubt as a virtue. This appears under the guise of confusing doubt with the "Dark Night" of Catholic mysticism. In this article, we shall contrast doubt with the traditional Dark Night and demonstrate that, while the latter is often a sign of emerging holiness, the former is nothing Christians ought to celebrate as a virtue.
What is Doubt? How Does Doubt Relate to Faith?
Doubt is a state in which the mind is suspended between contradictory propositions and is unable to assent to any of them. It is opposed to certitude. In the natural order, it is generally related to the degree of evidence in favor of or against a proposition. Doubt arises in one of two ways; that is, it is said to be negative or positive. Negative doubt means that there is absence of sufficient evidence for either proposition, making it impossible to render a judgment. Positive doubt means the evidence in favor of either proposition is equally balanced to the degree that assent to either is not possible. In either case, doubt exists when the mind is unable to assent to a particular proposition.
Notice the intrinsic connection between doubt and the presence (or absence) of sufficient evidence. Presumably, if the evidence for any proposition were sufficient, the person would no longer be in doubt about it. The doubt would give way to opinion, and if the evidence were strong enough, to certainty. But when the evidence is deficient in some way, the intellect cannot perceive the truth of a proposition and thus cannot assent. In inability to definitively assent is the state of doubt.
Notice also that doubt is distinct from denial. A person who denies a proposition has certitude, but their certitude is in the proposition's falsity. A person in doubt, on the other hand, lacks certitude either in the truth of the proposition or its falsity. They are suspended between contradictory positions and unable to find any certitude because the evidence is deficient, either in a positive or negative sense.
The question then becomes what is the relationship of doubt to religion, specifically to Christianity? And is there a positive place for doubt within the Christian framework.
We must first note that Christianity is a revealed religion, the assent to which is grounded not in knowledge of empirical propositions, but in faith. Faith is a type of assent that is based neither on empirical evidence nor on the intrinsic rationality of a proposition, but on the authority of the one who speaks. One who assents in faith assents not to evidence but to a person. The First Vatican Council defined the assent of faith as proceeding from the authority of God, who reveals the Christian religion:
This faith, which is the beginning of human salvation, the Catholic Church professes to be a supernatural virtue, by means of which, with the grace of God inspiring and assisting us, we believe to be true what He has revealed, not because we perceive its intrinsic truth by the natural light of reason, but because of the authority of God himself, who makes the revelation and can neither deceive nor be deceived (Sess. III, Chap. 3).
So faith is not dependent or derived from any sort of empirical evidence. This means that when we are discussing faith, doubt has no place. Doubt exists due to an insufficient amount of evidence for a proposition; but articles of faith do not depend upon empirical evidence, but rather on the authority of God. An article of faith must either be accepted or rejected; it cannot be doubted. This is why the Catholic Encyclopedia notes, "It follows that doubt in regard to the Christian religion is equivalent to its total rejection, the ground of its acceptance being necessarily in every case the authority on which it is proposed, and not, as with philosophical or scientific doctrines, its intrinsic demonstrability in detail" .
This means that doubt never has a positive value in Christianity; it is never an admirable thing to doubt articles of faith. Since articles of faith cannot be "doubted" in the strict sense, doubt amounts to rejection. The Catholic Encyclopedia continues:
The unconditional, interior assent which the Church demands to the Divine authority of revelation is incompatible with any doubt as to its validity...Doubt as to the Faith is thus impossible in the Catholic Church without infringing the principle of authority on which the Church itself depends...It will be evident from what has been said that doubt cannot coexist either with faith or knowledge in regard to any given subject; faith and doubt are mutually exclusive, and knowledge which is limited by a doubt, becomes, in regard to the subject or part of a subject to which the doubt applies, no longer knowledge but opinion. 
It is understood that persons may suffer from doubt against their will, or they may intentionally cultivate a skeptical disposition of doubt. But in either case, doubt is ultimately something that is antithetical to faith and should not be praised.
Crisis of Faith vs. Dark Night
Why do we insist on this notion that doubt is antithetical to faith and ought not be praised? Because, as we mentioned above, doubt has become so prevalent throughout modernity that many Christians suffer from it. To some degree, Christianity has tried to cope with the age of doubt by baptizing it into a positive virtue.
Occasionally it will come to light that some great figure of modern spirituality struggled with serious doubts about his faith, or suffered what is commonly called a "crisis of faith." And people - wanting to be able to affirm these people as heroes - will praise them for their crisis of faith, as if struggling through a prolonged period of doubt is something to be celebrated. Experiencing doubt, or having a "crisis of faith" - which could be defined as a period of prolonged doubt about the faith - is often equated with the "Dark Night" of Catholic spiritual tradition.
However, the Dark Night is something very different from a crisis of faith. A crisis of faith occurs when a person is perturbed by nagging doubts about one or more articles of faith. As we have seen above, doubt is an inability to assent based on a deficiency of evidence. Since faith is not subject to judgments based on evidence but on authority, a crisis of faith signifies a person is wavering between accepting or rejecting the claims of Christianity.
It is beyond the scope of this article to go into how one comes out of a crisis of faith, or the character of faith as a gift of God, but it suffices to say that wavering between belief and unbelief is not an admirable position for a Christian to be in.
A Dark Night, on the other hand, is something quite different. If a crisis of faith is a state where faith suffers due to persistent doubt, a Dark Night is a period when faith is strengthened by the soul's increased reliance on God. Traditionally, the Dark Night is a state of spiritual growth in which all tangible or sensory indicators of God's grace are removed, leaving a soul with a feeling of extreme dryness or spiritual aridity. Deprived of all sensible signs of God's favor, the soul is compelled to cling to God purely by faith; it is a means God uses to refine and strengthen faith by removing all external props to it.
Thus, a Dark Night is fundamentally different than a crisis of doubt. In a Dark Night, the believer does not lose faith but rather loses external consolations; in a Dark Night, faith is strengthened whereas in a crisis of faith it wavers. There is no doubting articles of faith in a Dark Night; rather, the articles are clung to more tenaciously as sensory consolations dry up - a crisis of faith, on the other hand, signifies that the person is plagued by doubt. And finally, while a Dark Night is often a sign of a spiritually sensitive soul in an advanced state of purgation towards holiness, a crisis of faith is often the sign of a spiritually unsteady soul whose faith may be in trouble. The Dark Night and the crisis of faith may seem similar in the sense that they are both experienced as crises, but that is where their similarity ends.
As we can see, it is nothing to celebrate when a Christian is in a crisis of faith or period of prolonged doubt. Doubt is not something to be celebrated as a mark of holiness, much less put forward as something normative for a Christian's faith.
To give an example. Suppose - just for the sake of argument - we had an ecclesiastical prelate who made the following comment:
"[Christians who] have not experienced a crisis of faith are missing something. On many occasions I find myself in a crisis of faith. Sometimes I’ve questioned Jesus and even doubted. Is this really the truth? Is it a dream?” [This happened when I was] a boy, a seminarian, a religious, a priest, a bishop and even now as Pope” 
If this statement was really made - if a prelate ever suggested that it was normal or admirable for a Christian to have doubt in Jesus, or to say that Christians who never doubted Jesus were "missing something" - that prelate would be fundamentally in error about the praiseworthiness of doubt.
And what of the faith of this prelate himself, who would boast in his habitual doubt as if it were normal? Given that doubt and faith oppose each other, we would conclude that the faith of this man was fundamentally shaky. Giving him the benefit of the doubt (pun intended) and assuming he has always managed to resolve his doubts in favor of faith, still, his faith would be very imperfect and would in fact be more of a kind of "probable opinion" instead of strict faith. The Catholic Encyclopedia notes that faith that is nevertheless punctuated by doubt has more in common with opinion than belief:
[D]oubt is sometimes said to imply belief; though such belief or practical certainty cannot properly be held to rise above the most probable kind of opinion. 
The Catholic Encyclopedia is certainly not authoritative, of course, and we cannot judge this prelate's soul, except to say that it is hardly laudable for a Catholic prelate to boast of his habitual doubt in Jesus Christ - and it would be horrendously reckless for the faithful, enamored by this prelate's reputation for piety, to praise this statement as if it were evidence of holiness. This would not be a sign of holiness or heroic faith, but of a faith so shaken by uncertainty that it had degenerated to the level of mere opinion.
Or so it would seem.
 (1909). Doubt. In The Catholic Encyclopedia. New York: Robert Appleton Company. Retrieved June 22, 2016 from New Advent: http://www.newadvent.org/cathen/05141a.htm
 (1909). Doubt. In The Catholic Encyclopedia